- [rst] option to build the library with t-state callback permanently
  disabled, but with full timings (contrary to Z80EX_OPSTEP_FAST_AND_ROUGH) 
  in this mode two macroses must be stripped down to:
	#define T_WAIT_UNTIL(t_state) \
	{ \
	  if (t_state > cpu->op_tstate) { \
	    cpu->tstate += t_state - cpu->op_tstate; \
	    cpu->op_tstate = t_state; \
	  } \
	}

	#define TSTATES(amount) \
	{ \
	  cpu->tstate += amount; \
	}   
  Z80EX_OPSTEP_FAST_AND_ROUGH must enable this mode automatically 

? BUSACK/BUSREQ emulation
