Fixed NMI Bug and updated test/debug outputs

Change-Id: Ie05ae9344242424d50af789c769805cdd57d998a
Increased Z80 clock from 6.144MHz to 7.98MHz as NMI timings seemed marginal

Change-Id: I40bc0c689e8eab78532c473a413b6994c721caa2
Re-instated what I think is the right nflag logic

Change-Id: Ibef96705a75ae5ba6d732eca73b68e3be4ba30f9
Fixed a confirmed bug with PH3 in Clk/Rdnw mode, which broke Save

Change-Id: I7b6dc2df2fd485eec3673ca71befa9b283ff51d8
Temporary fix to HP3 - WILL BREAK TWO BYTE MODEgitkgitk

Change-Id: Ie6e5345fce6acd4a73a6c40daf46dd6a1cf652b7
Fixed a reliability problem with the reading of the Z80 interupt vector; no idea why is was failing

Change-Id: Iefc01d163f86b84b3f1609cad776a152b3898d7b
Reverted Z80 clock back to 6.144MHz as change was unnecessary

Change-Id: I8d781a8174520b6ea232f4a4da2fab60f8e7ada9