Lot's of stuff, Read full Commit log

Cybernetic limbs
Multi-location operations
Limbs have sprites now (They never dropped before so it was irrelevant)
No Organic healing of Robotic limbs (But the message is still there, fixing soon)
No "organic" diseases in Robotic areas
No more operations in robotic areas - Cheer's Pete for the surgery system being so nice
Healing Robotic limbs with welders (brute) and cable (burn)
Probably other things I forget
Updates code/game/objects/items/stacks/medical.dm - Woopsie.
Became less selfish
Made it Easier to create your own Multiple location surgeries, updated surgery/multiple_location_example.dm to reflect this
Updated surgery/limb augmentation.dm to this new way of handling Multiple location surgeries.
YOU SAW NO TEST COMMENT!
Update for power code to remove some bugs and fix some functionality
Functionality
========
*Cables can now be placed across each other and not connect, just like cables placed in the map editor.
*Alternately by leaving a "node" or "dot" in both cables you can have these cables connect

Bugs Fixed
=======
*Unconnected cable networks which share the same powernet and power are no longer created when adding cable to nodes or removing nodes on top of smooth cable

Code changes:
==========
*Adds denode proc that should be called when a wire is added to causing it to no longer be a "node" (i.e. terminates in the centre of the turf)
*Adds propagate_network proc that traverses the graph adding every cable to a new network while removing the old one
*Adds call to denode in the cable_join proc
*Fixes mergeConnectedNetworksOnTurf() to only connect cables that are both nodes
*Adds a get_marked_connections() proc to cable which finds all edges connected to it's endpoints regardless of whether they have a powernet(as opposed to get_connections())
clarified a comment
Fixes #1716 as far as I have tested
Gives all turret cover types their own Ex_act's
prevents the gun from deleting the cover

Tested on
-Turret
-Just cover
-Porta_turrets
-Just porta turret cover
creating a get_marked_connections method for machines that doesnt check for powernet==null
making propagate_network non recursive
Fixes Chem healing and Chem damaging of Robotic limbs
Hey @Cheridan NO ISTYPES! :D
Ugh.. I mean "Removes" 10 totally unnecessary istypes
Fixes the healing of robotic limbs so that the message actually doesn't display now.

Credit to ACCount12 for digging around and finding some nifty code
that my brain never thought of
Fixes an earlier attempt at the previous commit
Fixes a comment that was a DIRTY LIAR
Adds a robotic limb heal proc
this is due to the original proc having a check in it now which saves us
millions of snowflakey checks, if you wish to heal a robotic limb use
heal_robotic_damage(brute,burn) it functions the same as heal_damage
but actually heals robotic limbs instead of organic ones

Updated the welding and wiring repairs to use this proc
New Human EMP_act
Old one was shite and I broke it somewhere
Fixes pipe bug.
Issue https://github.com/tgstation/-tg-station/issues/1669 and its duplicate https://github.com/tgstation/-tg-station/issues/1099
Fixes the HE pipes.
 * Simple animals will now consider invisibility when attacking and choosing targets.
 * Renamed SA_attackable to CanAttack(). Moved relevant code into there. Should make mobs more responsive with their targets.
vending system that use granular stock boxes
Attacking unanchored windows truns them into stacks of glass
removing unnecessary "/" from variant declaration
New system based on restocking points rather than fixed inventory.