homescreen widget for favourite stops

[rockgecko-development]

Feature: homescreen widget for favourite stops (#14) Add a homescreen widget/shortcut to a favourite stop to your homescreen, via the favourites context menu. This will need a new icon, at the moment it's using a very blurry star!

Future enhancement: support android 7.1 app shortcuts (by pressing on the launcher icon)

Also: -Use headboardRouteNumber instead of routeNo so it shows route 3a instead of 4 (which you can only notice on weekends!) -Fix some lint issues with menu item action view (would cause issues on Android<11)