Rework synchronization mechanism so Daijisho won't open lots of files simulateously

[shawly]

I wanted to use Daijishou to access my collection of backups through my network share on my home server. I used CIFS Document Provider so the File Manager can access the files.

The problem is, that Daijishou seems to open all files in a folder simulateously and never lets go of the file handle. This means that if there are over a hundred files and CIFS Document Provider is limited to 30 open files, Daijishou won't do anything after it has "scanned" 30 files. If I change the setting in CIFS Document Provider to allow 100 open files, Daijishou will simply crash after a while.

I don't see a reason why it has to open all the files simultaneously, so I guess the code is just inefficient.