The .tin/.tout pairs were not getting reset correctly with the other trefvars when a tie went away.
Also fixed an issue where all the trefvars would not get reset in the case where *.numties was non-zero but the tie port being attempted to read from was incorrect. Now bots can reliably check to see if a tie still exists by trying to read from the tie number. trefvars such as .trefxpos will be 0 for that tie port even when other ties still exist.