fixed an instance of unfair zombie tp

various improvements - thanks koen
fixed ending water being solid
fixed both bow items killing humans with physbox crushing damage
fixed some vertical doors crushing humans when touching item buttons
lowered alpha and brightness on potion items particles
fixed item pickup sound not being global
increased radius of the falling rock explosion
lowered difficulty of the last right jump at double lever trigger
made pressure plate trap harder to troll

Created ze_scourge_p.