NYT Next/Previous Crossword per Seb

On both the welcome and finish screens for the New York Times crosswords, this extension will add a "Previous Day's" and "Next Day's Crossword" button. Clicking this avoids the need to traverse through a lot of menus. Works on both Classic and Mini crosswords.

Known bug: The previous button will still appear on the oldest crosswords. I'm too lazy to fix this now but it may be fixed in the future :)