+Rearranged some code related to player controls that was accidentally badly placed.
+`ai_inactive` variable is now tied to vent hopping, so if there is a player in control, the AI should, in theory, not jump into vents while a player is in control. I hung around one for a minute and nothing happened. Could have been luck of the draw. Dunno.
+Brought down melee armor to 0 for the juvenile metroids.