Extends the cargo shuttle conveyor by one tile

Looks nicer.
Air alarms play a sound when there is an alarm
Added system for overmap building.
-metaboject with zlevel info that should be placed on sector/ship zlevel
-overmap object that represents a map zlevel
-startup hook for building the overmap
Increases air alarm sound delay to 20 seconds
Adds overmap system and examples of it's usage.
Unticked, as it disables space edge transition.
Added small readme file for overmap system.
Stunbatons now run on charge.
Adds improvised weapons.
Increases unarmed stun time, decreases push stun time.
Increases melee embedding chance.
Merge branch 'dev' of https://github.com/Baystation12/Baystation12 into robust-squash

Conflicts: lots
Implemented suggestions from PR
Adds interface to the helm console.
Added ship movement delay.
Made autopilot actually move ship towards destination.
Improves suit cooler

Adds a few vars items should have, e.g. throwforce, flags, etc. Also
origin_tech.
Merge remote-tracking branch 'upstream/dev' into air-alarm
Merge pull request #5403 from mwerezak/suit-cooler

Improves the IPC suit cooler
Merge pull request #5398 from comma/overmap

Overmap
Fixed battery draining computations.
Merge pull request #5400 from comma/robust-squash

Robust squash
Merge pull request #5382 from mwerezak/air-alarm

A couple small things