Work on thumbsget4linux so that Linux users aren't left out.

Currently, there's the original Windows version along with ports for Mac and the web/an HTML file. While Linux users can use the webpage version (or maybe the Windows version under Wine), I'd rather there be a better desktop experience for them. Porting thumbsget to Mac will probably help since it required learning some C#, which doing thumbsget4web also helped with since JavaScript seems to be a "simpler" version of C# in a way.