added todo document and more comments to code

Author: tnibert

TODO.md

@@ -0,0 +1,8 @@
+This is the list of project goals to be implemented:
+
+1. Improve boss AI
+2. Add power ups, e.g. more bullets fired at once, force field, etc
+3. Improve game art, especially start and end screens
+4. Add in high score save and display functionality
+
+These will be described more in the issues section