reduce number of wait states in ReservationStations2 by detecting

reduce number of wait states in ReservationStations2 by detecting
opportunities for sending (and receiving) data immediately.

the previous version was a 4-cycle FSM.  however it is perfectly
fine to detect, in the very first phase (as part of ACCEPTANCE),
if the ALU is already ready to accept.  effectively this combines
phase 1 and phase 2.  if the ALU was *not* ready then and only
then will a given FSM move to phase 2 (after buffering the data)

likewise, when data comes out of the ALU, there is an opportunity
to signal to the RS output that the data is in fact ready... *if*
the RS output was in fact waiting for it already.  again, this
combines phase 3 and phase 4.  again: if the RS output was not
ready, then a given FSM will move to phase 4 (again, after
buffering the data)