Create commits from worktree event queue. (Linux only now)
[client] Remove GC and clean up local blocks after repo is synced.
[client] Get worktree event detail on Windows.
[client] Fix a bug on worktree watching on Linux.
[build] Add CMake Build System

  - remove key storage stuff
  - fix daemon build under osx with cmake
  - Set SOVERSION of libseafile to 0
  - remove shared library version
[common] use packed attribute if available
[cleanup] silence multiple compiler warnings

  - silence the warning of uninitialized head_id in putcommit-v2-proc.c
  - silence the warning of implicit declaration of g_open in test-seafile-fmt.c
  - silence the warning of implicit declaration of g_stat in test-cdc.c
  - silence the warning of uninitialized e in merge-recursive.c
  - silence the warning of bm->size >= 0 is always true in fileserver.c
[build] cmake patch for new-sync
[build] more cmake fixes for new-sync
[client] implement new changes of wt-monitor in osx