file name check should only consider letters and numbers

[B1ad3]

I hate it when the professor uploads files but uses underscores at the first and hyphens at the next for example. My problem is that they get sorted wrong in the explorer and when I change the file name sync-my-l2p just downloads the file again. So if it only considers the letters and numbers in a file name, the problem should be solved.

[detzt]

I would say only considering letters and numbers can lead to a whole set of new issues. Instead it would be better to rename something inside SML2P so it would be stored which file on the server the renamed file correspondends to. This may not be as simple as ignoring other characters, but can provide additional features like updating even a renamed file.