Changes
- support landscape view
- support server side thumbnail
- change descriptional texts of subtitle to be last modified time
- hide Activities tab and search function on community server edition
- support cache starred files
- support auto upload videos
- support auto upload from custom folders
- support Czech translations
- optimize document provider (SAF)
- Support writing (uploading) files
- Support creating files/directories
- Show starred files
- Improve repository list: use Seafile icons for repositories, show descriptions
- fix: don't allow user to enter encrypted repos
- improve account (root) list: display account email address in 2nd line
- use a thread pool for concurrent tasks
- remove verbose FileNotFoundExceptions
- some refactoring
- some small fixes