prevent memory leak from RepoTreeModel
add initial support fot doxygen-generating

how to use it
1. cmake .
2. make doxygen
3. open docs/index.html
fixed jpg/image files auto upgrade on macos
Merge pull request #329 from haiwen/doxygen

add initial support fot doxygen-generating
Merge pull request #221 from Chilledheart/patch-1

prevent memory leak from RepoTreeModel
use transfer mgr to manage upload/download tasks
fix a potential bug with readlink(2)

According to linux manual READLINK(2)

   readlink() places the contents of the symbolic link pathname in the buffer
   buf,  which has size bufsiz. readlink() does not append a null byte to buf.
   It will truncate the contents (to a length of bufsiz characters), in case
   the buffer is too small to hold all of the contents.

there is a situation that readlink returns bufsize when the path is long enough
, and in that situation we would write \0 to the invalid address buf[bufsize].
obviously it is not allowed.
display download progress in file table
work aroud mac image auto update problems when openning starrted files
Merge pull request #229 from Chilledheart/patch-4

fix a potential bug with readlink(2)
should not read dirents from cache when refresh failed