Some work towards proper asset disposal.
Switched to a buffer pool for managing VBO disposal (the cause of the crash when actually deleting buffers eludes me, but this at least means the VBOs can be cleared and reused).
Switched to using an integer rather than byte buffer for populating the main chunk buffer (due to reputed better driver support)
Improved Tesselation of double sided block meshes (halves number of vertices).
Added buffer pool size tracking.