#16 Removing duplicate tiles when Importing Tiles

[weirdmusician]

I've found I can just capture a whole screen shot and
line up the margins correctly and scan in a whole
screenshot of tiles, and if tilestudio could just removing
any duplicated tiles that are being import or that are
already in the loading set when it imports from my
screeny that would be awesome, and save a lot of time
in ripping sprites. thanks.