Two bug fixes in SideWinder version of Plover

If you go over to the Github, you'll see changes in tktest.py and sidewinder.py. I recently took a trip to Seattle and Missoula and didn't have enough room in my luggage for my steno machine, so instead I took along the new SideWinder X4 I bought for my brother William. I had four transcription files to finish before the end of the trip, and I discovered that the freezing bug which had intermittently affected Plover completely prevented me from using my rewind foot pedal with Winamp, so my brother and I sat down together and fixed it, by gum. I also put in a line of code that made it so if you accidentally hit the space bar (like I found myself doing constantly, since it's so close to the vowel keys) it doesn't throw out the stroke the way it does if you hit other keys besides the ones mapped to be steno keys; it just ignores the space and translates the stroke as usual. These two tiny little changes has made Plover drastically more useful as-is, and tomorrow I'm meeting my Python tutor to work on keyboard emulation. I know it's been a bit of a hiatus, but Plover is back in active development again.