Entered() cleanup

Cleaned up the turf Entered() procs:
-Removed check for infrared beams. (it checked each time that anything moved)
-Removed 'movement_disabled' check, the verb is also completely removed.

For space Entered() turfs:
-Removed check for meteor
Now meteors and immovable rods will use the same proc to determinate their start and finish, while moving they'll check in which z level they are, deleting themselves if they leave it.
-Removed spawn() to move objects being pulled between z levels
Replaced the step() from mob pulling movement code and replaced them with Move()

For asteroid Entered turfs:
-Removed check for mining cyborgs, now it will be next to the janitor borg check to clean the floor.

Mecha code got a small clean, removing the Entered() calls from there.