make M/m command without argument continue from previous offset.
fix bugs in MAP memory map address calculation. Issue #30.
fix bug in M/m command without arguments.
fix numerous bugs affecting loading of ROM file.  ROM file now appears
to be loaded correctly.  Issue #30.
try to start ROM after loading.  There seems to be some memory map
problem preventing the ROM from starting properly. Issue #30
fix bug with M/m continuation.