#350 Add option for single folder extract

[Miloš Stojanović]

When I extract files, most of the time I want a single folder as a result. I could just always use "Extract to <archive_name>" but I don't want to have multiple levels of single folders in the hierarchy. So the process I usually use is:
1. Open archive to see if it contains only contains one folder
2. If it does, use "Extract Here"
3. If not, use "Extract to <archive_name"
It would be nice if this feature was in the aplication itself.</archive_name>

In the attachment is a suggested patch with some pseudo code in the main function.