Player sprites : left & right
display: zoom
level: fix fantom entities being rendered
level: order entities by their Y position
Zoom fixed, coherent entities/level size
Added player's movements frames while going down
level: fix y-reordering
made window size consistent
fixed entity sorting
input: fix mouse position
made pixel size 2px
centered button
entity: remove getFriction
Merge branch 'master' of https://github.com/Aomeas/1GAM1014