Changes

In fact it is more difficult instruction that I was thinking, if you watch at it, it shall take only 4 NOPs maximum but in plustest.dsk it does take 6/4 NOPs. In fact C9 RET seem also used here, as sub instruction. Do remark that CPD and CPI does take 4 NOPs, so here CPDR/CPIR does not has same implementation than CPD/CPI.

==== Z80: TODO : cpc-power testbench ====