Truce changed to Planar Calm

Replaced Truce with a spell called Planar Calm. This new spell has a spellpower-based chance to close any Shadow Rift portals in the room, and also calms monsters for up to 4 seconds.

This replacement serves the dual purpose of eliminating Truce and also giving us a utility spell to close pesky Shadow Rift portals. I modified and renamed the existing Truce spell to avoid any issues deleting and replacing the spell might cause.