Allow more ways of selection of directories for cm_FileSync

[umbra]

Currently, cm_FileSync always compares directories opened in two main panels.
But it would be handy if I could select the directories the same way as I can select files for cm_CompareFilesByContent - by simply marking those directories in one or both panels.

[ghisler(Author)]

Marking directories has a different meaning in cm_FileSync: It is used to tell TC to only compare the selected subdirs! for example, you could have folder "My Documents" with subfolders "Letters", "Faxes" and "Excel". If you want to sync only "Letters" and "Faxes" between this directory and a backup directory, you can select the two and then open the sync tool. TC will then check the option "Only selected (main window)".

[umbra]

Right. I didn't realize it would collide with this feature since I'm not using it very often. Ok then, it's not a big issue.