Merge branch 'daily_nobuild'
update version to 2.1.0

1. introduce awsome plugin infrastructure
2. new markdown plugin for render markdown notes
3. notes comments support.
4. drag-drop pictures to note view support.
5. several bugs fix and enhancements.
fix build issue on linux with Qt5
scroll per item on linux
fix gui dead-lock issue when request token
bug fix: parse comments count json failed lead broken issue
enhancement: icon background drawing issue
fix QtConcurrent reverse build issue on OSX
enhancement: change "document" to "note"
update markdown plugin to support more languages