Need to have the called provide a copy of the base line address to the
masked drawing code and need to verify that the JTable entries are
ordered the same way as the byte offset so the same register can be used
to load the JMP addresses and patch in the LDA (DP),y instructions.
This is not quite correct yet. IT appears that two rows or columns are
drawn on the edges when only a single solumn or row is necessary. Also,
this code is based on the old GTE codebase, so the initial rectangle for
rendering tiles is width+1, height+1. This can be improved.
