Strato-Scruffy Demo 5.1

Few little balancing changes and bugfixes:

• Enemies and bullets now do much more damage to you. To compensate, you now have a visible hitflash, and enemies will drop hearts that you can heal yourself with.
• You can now strafe! X will strafe while C is now the powerup button.
• Few very small level design and boss tweaks. There's some more major ones I'd like to do but I'll save that for the next update