Merge with Rebase

Fix freeing some reference counted pointers so that underlying memory is properly freed.
Also fix the cleanup in some classes that were not clearing dependent objects.

Will be checking for more so left this as draft for the moment.
EDIT: This should be good to merge now, the memory leaks it fixes are some of the most prominent that i came across.

Fixes:

• Gen + ZH - ~W3DLaserDraw() was leaking materials.
• Gen + ZH - ~ProductionUpdate() was leaking production queue items if game exited before buildings sold or destroyed.
• ZH - Snow system was leaking on shutdown, wouldn't affect runtime but means a clean shutdown.
• Gen + ZH - ~W3DTankDraw() was leaking particle systems, therefore leaking particles as well.
• Gen + ZH - ~MeshModelClass() had an extra call to free directx8 references in the wrong place, this could cause other dependent assets to not be deallocated properly within reset(). And Generals behaviour was freeing data in the wrong order.
• Gen + ZH - Win32LocalFileSystem was leaking Win32File handlers due to creating a handler and returning early on a null filename before deleting it. Moved the creation of the file handler after the early return and where it is needed / used.
• Gen - ~MeshModelClass() was calling the wrong delete method when deallocating GapFiller data. Fixed already in ZH.
• Gen + ZH - Win32BigFileSystem was leaking Big32File handlers due to creating a handler and returning early on a null filename before deleting it. Moved the creation of the file handler after the early return and where it is needed / used.
• Gen + ZH - ~W3DDisplay() was not releasing its debug display string so it could prevent DisplayStringManager from being cleanly destroyed.