Fixed the bug preventing new articles from being stored after shutting down the extension

New features:
Added detection of GitHub releases feed
Made statusbar always visible to prevent content shifts
Added slight color change to active pane to make it easier to see
Added toggle buttons for sources list to show only sources with unread articles and for articles list to show only unread articles
Added per-domain throttling to reduce server load if multiple sources from the same domain are used
Added ability to detect redirects and update source URL accordingly

Bugfixes:

Fixed issues with saving of Feed or Folder properties
Fixed some issues with keyboard input
Fixed issue preventing articles list from being rendered in certain cases
Fixed search box
Improved article change detection
Fixed Youtube detection mechanism

Updates to change detection mechanism caused some malformed feeds to always be recognized as updated, this patch works around all the identified issues, if you still experience articles being marked as unread despite no apparent changes please report feeds affected by the issue in #183

### New features:
- Added configurable hotkeys - functionally complete, but displayed names of actions are a mix of translations, English strings and internal action names
- Added Mozilla Readability parser to optionally load article content from website - you can set it as a default view per source and toggle view using new button above the content
- Added support for multiple enclosures - Media RSS may include links to multiple files, now all of them are loaded from feed and displayed (items parsed in the past won't automatically load additional links though)
- Now Youtube embed won't be loaded instantly, instead the cover image is displayed and gets replaced with player on click to save resources
- It is now possible to open reader view before background task finishes loading, for example you can pin the reader tab and it will work properly after browser restart
### Bugfixes:
- Fixed issues with HTML entities in content body and header link
- Fixed issue causing some data to not be updated when article gets edited
- Improved display for Youtube descriptions (thanks to @akizuha for contribution)
- Fixed Youtube video ID recognition (thanks to @akizuha for contribution)
- Fixed issue causing `Never` option to not be properly displayed when selected in various places of feed properties
- Hopefully fixed issue causing new items to be put in wrong order when currently displayed feed gets updated, will keep monitoring this as it's tricky to reproduce
- Fixed issue that caused last release to mark articles as unread every time it updated feed
- multiple smaller fixes that weren't tracked
### Internal changes:
- Work needed to make configurable hotkeys a reality included also groundwork for options translations, but that's still a very distant goal

### New features:
- Added configurable hotkeys - functionally complete, but displayed names of actions are a mix of translations, English strings and internal action names
- Added Mozilla Readability parser to optionally load article content from website - you can set it as a default view per source and toggle view using new button above the content
- Added support for multiple enclosures - Media RSS may include links to multiple files, now all of them are loaded from feed and displayed (items parsed in the past won't automatically load additional links though)
- Now Youtube embed won't be loaded instantly, instead the cover image is displayed and gets replaced with player on click to save resources
### Bugfixes:
- Fixed issues with HTML entities in content body and header link
- Fixed issue causing some data to not be updated when article gets edited
- Improved display for Youtube descriptions (thanks to @akizuha for contribution)
- Fixed Youtube video ID recognition (thanks to @akizuha for contribution)
- Fixed issue causing `Never` option to not be properly displayed when selected in various places of feed properties
- Hopefully fixed issue causing new items to be put in wrong order when currently displayed feed gets updated, will keep monitoring this as it's tricky to reproduce
- multiple smaller fixes that weren't tracked
### Internal changes:
- Work needed to make configurable hotkeys a reality included also groundwork for options translations, but that's still a very distant goal

Fixed issue with auto cleanup, read entries won't be wrongly removed anymore

- Improved favicon handling greatly, now it won't get stuck on errors and is less likely to not detect favicon when one is available
- Fixed issue with automatic removal of old articles
- Fixed counters not updating properly
- Fixed content height not being set properly in some instances
- Added experimental support for feeds with prefixed tags (currently only tested on anidb)
- Added quick Spanish translation

Added option to show only sources with unread articles + toggle button on toolbar
Added button to remove selected source
Added button to scroll selected source into view
Added indicator of unread articles for pinned group
Added option to choose favicon provider - defaults to internal
Fixed auto removing old items from trash
Fixed automatic media preview not working
Fixed rendering issues when quickly switching from source with a lot of articles

- Added ability to automatically pin articles matching predefined filters - comma separated list in settings
- Fixed issue causing detected sources list to become empty when switching tabs

Added option to keep unread or unvisited articles when automatically removing old ones
Added `Subscribe` item to link context menu in case you find a link to feed that wasn't detected automatically (note: it appears on all links, not only ones leading to feeds)
Improved detection mechanism for YouTube
Improved handling of HTML entities
Cleaned up the look of content pane when no article is selected
Fixed issue causing feed detection to not list detected sources
Reduced size of the package

Added option to display source favicon when listing All sources or Thrash
Fixed feed detection issues
Improved favicon loading
Fixed sorting not working initially

- Changed the way articles list is rendered to prevent UI locking
- Greatly expanded feed detection capabilities (now supports Youtube, Vimeo, BitChute, LBRY and more)
- Added embedded video to Youtube feeds in the media area
- Improved translations (thanks to community contributions)
- Cleaned up Settings page - less scrolling, less clutter
- Fixed some other minor issues

Added ability to choose when New feeds found icon should be displayed
Added ability to hide already subscribed feeds from subscribe list

Added few of missing translation lines (thanks to joberreiter)

Fixed issues with Properties panel rendering for folders and when multiple sources are selected

Fixed Refetch function not working
Improved automatic housekeeping
Added button in Options allowing user to force clearing removed items cache
Hopefully fix Settings not loading issue

Fixed Refetch function not working
Improved automatic housekeeping
Added button in Options allowing user to force clearing removed items cache

Fixed `Title is link` not working in last version
Fixed issue causing different feeds pointing to the same items to not work properly
Improved import experience - file name masks are applied in file picker and now SMART import automatically overwrites data

Modified internals to render views according to AMO guidelines
Fixed Source list sorting to work properly with accented characters
Search now works also when you type unaccented characters
Fixed issue causing unresponsibility of interface during data load