Ports /tg's cable and powernet code to our code base.
Cherry picking breaker box fix.
Adds diagonal cable check on breaker box state change.
Basically ripped over /tg/'s powernet and cable code into our own codebase.

Keeps Z-level code as it was.
Modifies/restores powernet procs as necessary to match our own implementation changes.
/tg/'s solar code with a fix for the solar control computer not refreshing on user input.
Converts all machines relying on RandomAPCWires() to the new wire datum system.
Fixes bad tabbing, only evident when placing Z-crossing cables.
Sets turn-off limits based on a standard cell's max charge
Master controller no longer annihilate powernets, powernets annihilate themselves.

Some misc. changes.
Replaces add_load with draw_power. Issue about silly battery handling remains. Fixes the build-error.
Merge branch 'dev' into PowerTwo

Conflicts:
	code/modules/power/solar.dm
Restores APC load balancing and the autoflag system.
Merge pull request #6651 from PsiOmegaDelta/PowerTwo

Ports /tg/'s cable and powernet code