0.8 Update, Day 4 - New Game Mode: Endless Wave

Day 4 of game development... not really full days of work, more like working a bit here and there on it in the free time.

Added a new game mode with an endless wave of medium difficulty enemies. Beating 3, 4 is possible, but tough...

Surprisingly the feature was implemented extremely quickly, but 80% of the work time had to be spent on lame bugs like rotating ships, wrong visuals and similar things, which were not breaking the feature, but were just too stupid to look at.

Another lesson to learn: Use more git commits (save points) of the files... you never know what may go wrong on the way...