Fixed MEMPTR emulation on the CB indexed instruction group
Some GL optimizations
A provisional, quick-and-dirty test program (MEMPTRCB.SNA) is enclosed to check for MEMPTR completeness (z80tests fail to detect a lack of indexed CB MEMPTR emulation). PRINT USR 32768 should render the following results:
144: Spectaculator and Sinclairean B9
176: FUSE
184: SpecEmu and Sinclairean B10 REV. B (correct CB MEMPTR emulation)
