This is meant for a "permanent" tear-down before freeing the memory
holding the VM state or at program shutdown. As a consequence, builtin
sub-systems registering resources are now required to pass a "destroy"
function pointer that will be called just before the memory holding
those resources is freed by the VM resource manager (ie, the manager
owns the resource memory block, but each subsystem is responsible for
cleaning up any resources held within that block).
This even enhances thread-safety in rua_obj (there are some problems
with cmd, cvar, and gib).
The scene id is in the lower 32-bits for all objects (upper 32-bits are
0 for actual scene objects) and entity/transform ids are in the upper
32-bits. Saves having to pass around a second parameter in progs code.
I meant to do this a while ago but forgot about it. Things are a bit of
a mess in that the renderer knows too much about entities, but
eventually the renderer will know about only things to render (meshes,
particles, etc).
I've run into a bit of an issue with transform management (really, just
need to make them owned by the scene, but that means creating a scene
for quake and quakeworld).
