The previous texture_memory_alloc.hpp was written based on an
incorrect understanding of the "32-bit" and "64-bit" texture memory
address mapping.
The primary motivation is to rearrange the texture memory address map
so that "textures" (64-bit access) do not overlap with 32-bit
accesses, such as REGION_BASE or PARAM_BASE.
This fully threads both the real minimum size of the texture and the
dimensions of the texture through to the TA parameters.
This also removes spurious zero-area drawing commands (space
characters).
