Some of them, especially in rua_obj, were quite legitimate and even a
problem for thread-safety (rua_cmd is currently not thread-safe, but it
needs a lock, which I don't feel like doing at this stage).
It should have been this way all along, and it seems I thought they were
when I did rua_gui.c as it already freed its resource block, which would
have been a double free (oops). Fixes an invalid write when shutting
down progs in qwaq-cmd (relevant change not committed).
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).
Just "loading" and "unloading" (both really just hints due to the
caching system), and an internal function for converting a handle to a
model pointer, but it let me test IQM loading and unloading in Vulkan.
