Swapped vactube glass models for single sided ones to fix missing model errors.

Moved droppers.
Changed standard cube dropper to not auto-respawn.

Cube dropper in main chamber now only spawns one cube.
Prevented ninja trick to teleport cube into button room using angled cube.

Fixed player not starting with a portal gun (point_clientcommand).
Prevented climbing over the exit wall by adding a square.
Extended glass.