Small tweaks all around to handle UI mirroring:
- swap existing symbols like arrows, or use alternative ones
- rotate some images, like chevrons and dogear icons
- flip some left and right swipe handling
- flip some geometry arithmetic like tap on left or right
side of page or dict window
- use new ProgressWidget:getPercentageFromPosition() instead
of geometry arithmetic
- BD.wrap() some concatenated string bits, like in reader
and menu footers
- flip inverse_reading_order when UI is mirrored
More specific tweaks:
- ReaderGesture: reset some specific gestures when UI direction
has changed (tap on top/bottom left/right corners, for
bookmarks and FileManager "Plus menu").
- ReaderRolling: show markers on the correct side of page,
in single or dual page mode.
- KoptOptions: swap left and right icons in Alignment toggle
- CheckMark: proper rendering in all 4 mirroring/rtl combinations.
- VirtualKeyboard: forbid any mirroring
- Move util.getMenuText into Menu.lua
