Fixed big mistake about the frametime limiter : it's not FPS, it's an interval !
Added path and alias info in asset loading debug messages
Implemented entity hierarchy through a Transform object, roughly tested it in the demo
Added Entity hierarchy feature and rewritten stuff
Changed demo headers from "SSM" to "DEMO" (also removed the fancy comment about the game they were part of)
Fixed potential nullptr when playing an animation with a fixed number of loops
Removed TODO item, it's not really relevant now
Added more comments