Changes since 4.0-alpha2:
- upgrade Bangla dictionary, by @RHJihan (#2574)
- add Toki Pona layout, by @dsremo (#2575)
- internal refactor for sanity, mostly by @devycarol (#2252)
- update list of punctuation symbols (#2493)
- add link to community part of readme in about section (#2566)
- avoid spellchecking some inapplicable "words" (#1102)
- make automatic input of shift-to-capitalize word optional (#2317)
- Korean combiner now ignores emojis (#1896)
- add setting for key hint font size (#2106)
- add colors for emoji search to "all colors" (#2442)
- workaround for Android 6 being unable to rotate some images by 90° (#943)
- distribute toolbar keys evenly over toolbar (there were some issues, may search later)
- keep all applicable dictionary information in background data gathering
- minor fixes and improvements