extracted Entity superclass from Avatar
using Entity instead of Block and Avatar where possible. Avatar updates itself instead of being updated explicitly by the WorldController
minor
simplified event handling by using polling
added gfx resources for particle effects
minor
minor refactoring
refactoring WorldController
added ParticleScreen and adapted MenuScreen accordingly
added state to Projectile
wip: adding explosion handling and rendering
WIP: no more explosions created for already exploding projectiles
WIP - particle explosions - added dedicated SpriteBatch
WIP - explosion placing fixed
added Explosino entity - not integrated yet
corrected angle of explosion effect
reduced shot freq with weapon cooldown
WIP - refactoring
minor
moved explosions to World, explosion handling to WorldController