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
creating a get_marked_connections method for machines that doesnt check for powernet==null
making propagate_network non recursive
Fixed some container escape issues
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.
Fixed being able to escape moving lockers
vending system that use granular stock boxes
Fix for being unable to unwrench vents
Attacking unanchored windows truns them into stacks of glass
removing unnecessary "/" from variant declaration
New system based on restocking points rather than fixed inventory.
* AIs can no longer intercept messages randomly. Instead they can use the Message Monitor by getting their cyborg to get the keypass.
* The Captain's PDA no longer starts off, instead their PDA is detonation proof.
 * Made wet floors use a static overlay.
 * Standardized the wet floor code, it is now called MakeSlippery(var/wet_setting)
 * Added the wet floor static overlay, which is just a single frame of the usual animation.
 * Made the floor randomly dry (by a few seconds apart), for visual effect.
More code, vending machines cannot dispense while they are unscrewed. (might remove that)
Only the dmi files are missing now.
Merge branch 'master' into vending-reloadedB
 * Quick bug fix with latejoin double agents.
Some extra comments and an extra check for unscrewed panel