* DONE for all asset types, make the Director define load*()
* DONE instead of requiring Cloneable<Set>, add Director.cloneSet()
* DONE in all newMethods take a path, not the object.
** DONE allow for alternative loading with the object directly, like how some props in HollywooFlixel are animated via ActorFlxSprite
** DONE if the assetpath doesn't start with assets/, call (assetPath "<typeDir>" "<path>")
** DONE make loading things at runtime a compiler error 
* DONE try disabling AssetCache completely
* DONE in all with_ macros, mark those assets as dirty (needing to be reloaded)
* DONE Movie.scavenge before cleanup
* DONE in all new* methods, don't load the new thing if it exists already