0.7.5 release: a bug fix, and other things — Mysterious Space Steam update #1046224

I fixed a crash when your second armor took damage and you had no first armor equipped! A very rare/obscure situation that I might have never found on my own, so thanks to whoever sent that crash report! Unfortunately, the music-related crashes that some people are experiencing still aren't fixed. From the crash reports you guys have been sending, it really looks like an issue with MonoGame (the library I'm using). I've filed a bug report with them: https://github.com/mono/MonoGame/issues/3884 hopefully they can figure something out, even if it is "er, no, it's YOUR fault, do X in your code to fix it." that would be great :P A couple other changes this release: 1. I got to chatting with a guy from groupees.com after sending them the Steam keys, and we realized that the game would be a little more exciting if the rate enemies spawned SPED up over time, instead of slowed down! I had made t...