v4.6.0: OpenTracks

Changes:
- Voice announcements use ICU plural format (en, es, pt, zh, dr, de) due to fractional quanitites #1584
- Requires Android 7.0 / SDK24+ due to ICU plurals
- On Android 14+: use Android's AltitudeConverter instead of internal EGM2008

Bugfix:
- Android 13 couldn't select images from gallery

Developer:
- Split ActivityType and ActivityIcon