Upgrades!

Upgrades here we go!

After some feedback I introduced some upgrades to the game.

So far there are 7 of them:

• 3 related to HP
• 3 related to shooting
• and final one is related to movement speed

You can access them from the Alien Shaman and Destroyed Rocket.

Besides that few new floor tiles were added for each type of room. New drop item for Red Alien enemies and many more small things I don't remember.