Fixed index of canvases in effect composer
moved generic stuff into loverman.lua
Moved PostEffect class to effect_composer.lua
Moved bomb collision code into callback
Moved tank and powerup generation into a callback which is called after new terrain has been generated
Fixed bomb dropping code in player
Adapted tank code to new circumstances
removed gamestate dependence of subsystems
moved camera dynamics into a subsystem
using subsystem updates instead of manual updates
cleanup of main