Add plugin doc
Feature added: profile widget
bug fix

1. Can remember last scroll position when switching tab now
2. Can auto resize tab when switching tab now
bug fix: unhandled exception when failed to retrieve image
bug fix: gif displaying problem in PictureViewer
record history of timeline, comment, mention into database
load history data from db when initialized
add network option
daily commit
bug fix: proxy problem in plugin.getData
auto update account group when accounts added/deleted
update README.md