Reduce Virtual Address Space usage

[kirides]

We are limited to 4GiB of virtual address space. We should ensure we don't hold on to it if not absolutely necessary.

We should ensure the engine properly caches-out unused textures as well as our "engine surfaces"

Generally, we should figure out where our virtual address space is getting reserved and find out how and if we can improve it.

Progress:

• We now use the same allocator that gothic uses, which should improve memory management, as the allocator is now aware of all allocations. Previously we had two allocators fighting over memory. zAllocator, string usage optimizations, VDF file support for renderer resources #367
• we removed the per VOB/MOB constant buffers in which drastically reduces memory usage.fix: remove per Vob/Mesh constantbuffers, large memory usage reduction. #370
• We also fixed a memory leak for Pointlight shadows in fix #373 - always update particleFX if close to player, fix pointlight memory leak #375