[client] land new changes of new-sync for osx
[win] Fix a memory bug when unsyncing a library.
[win] Fix command handling bug in wt-monitor.
Update msi version to 3.1.1.
[win] Fix command handling bug in wt-monitor.
Merge branch 'new-sync-osx' into 3.1
[client] make the compiler happy when compiling with -Wall flag
Merge branch 'master' of https://github.com/haiwen/seafile