v68k:  Move decomposed SR to its own struct

The status register members are no longer initialized in the constructor
of processor_state, but they remain initialized by emulator::reset().
v68k:  Use pc() accessor for regs.pc
v68k:  Add remaining control registers
v68k:  Replace registers struct with array
v68k:  Avoid d() for non-data-registers
Merge branch 'v68k-register-array'