Allow Target Directories to be added manually

[ksihota]

It appears that the directories used for comparison must be the ones listed and there is no recursive search.

Edit: Based on some tests I have made this may or may not be true. In some runs, the comparison found duplicates in sub directories (not explicitly stated) and in a couple others no duplicates were found in a defined directory that did have sub-directories that held duplicates. Maybe it was some error I made.
Maybe this needs to be specified somewhere. I couldn't find the information if it is.

In the case where a recursive search is not available, it would be much easier to enter directories manually without the multitude of mouse clicks. It would be nice to be able to add a new empty filed and then type in the directory, or even better to be able to add an original path and then a series of sub directories within that path.

Example I could type in:
/home/files/photos/dir1/sub1
/home/files/photos/dir1/sub2
/home/files/photos/dir1/sub3
or even better
/home/files/photos/dir1/[sub1,sub2,sub3]

using some similar syntax
rather than mouse clicking to do it.