-added 'dot' function to vector math
-fixed Circle tool rendering
-fixed some potentiall memory leaks
-added 'collision' module which now separates ShootGrid from SpaceInvaders demo
-separate some systems from demos to 'basic' module to better demos functionality sharing
-slow down snake
-added new graphics
-BrickBreaker demo now works (without blocks breaking and with bugged collision detection)
-some bug fixes