Interporter update (1.1)

This is an update of the Interporter by Mugendai to fix the teleport sound being
cut off when a creature teleports. The sound is now emitted locally from both
teleporters as opposed to being attached to the creature.

It also includes the stim fix script that was released later. Note that there is
also a stim-fixed version released by Verm, but that was based on the version
with the sound following the creature.

Credits
-------
Original agent:  Mugendai
Stim fix script: (unknown)
Other fixes:     Emmental

Version history
---------------
1.1
- Portals can no longer be used (either as a source or destination) if carried.
- Portals (when opened as an actual portal) no longer bounce when dropped.
- The destination is now first checked for space before a creature teleports.

Emmental
https://github.com/chiizujin/edsa
