TLB cache fixes

Updated C bit on TLB cache hits.
Added TLB state to the save state file.
Removed the tag check in InvalidateTLBEntry. All four TLB entries are always cleared on each invalidate command.
Initialised the TLB cache to start from a consistent state on reset.


Yes, with the current code, both TLB[0] and TLB[1] might end up caching the same address.  I cannot think of a clean way to detect this situation - PR's welcome