Adding a dev_mvme187, for MVME187-specific devices/registers.
Implementing subu.co (guess), addu.co, addu.ci, ff0, and ff1.
Implementing the M88K xmem instruction.
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Adding Miod Vallat to the thank you notice; Miod sent me M88K manuals :)
Removing the unused tick_hz stuff from the machine struct.
Optimizations for addu r,r,1 (r++) and subu r,r,1 (r--).
Fixing bugs in 64-bit (32-bit pairs) M88K loads/stores.
