haul in the decorators, we're using the tiled-horizontal decorator

as a base. hopefully it will be sufficient.
actually, import the invader example decorator.
make the sprite dtor virtualized.
even better, use the defender instancer
add instancer
stop light renderer's flickering..it was intentional, but it doesn't

look good at all
allow turning off tile rendering via f10
proof of concept of inventory slot decorator
improve Image class file non-existent handling (by using sys/stat.h)

lots of debug output improvements around librocket renderer/decorator.
clean up a lot of it, now the spritesheet decorator can be created without
having a valid property image set. and it will also try and switch the
image texture mid-rendering if the property gets changed.
quiet debug in decorator, fix warnings by casting stuff
nearly there at setting texcoords for decorator
texcoords left/right are fine
texcoords now work properly, time to set them from the inventory..
dynamically set the inventory item icons now, the spritesheet

and s,t are hardcoded for now though
the inventory looks up spriteframeidentifier from the spritesheetrenderer

and sets the x1,x2,y1,y2 texcoords on that item. works wonderfully.