Cleans up used_radios

The used_radios handling was too specific to be in mob/living/say.
Subtypes had to figure out what to pass for used_radios anyways, they
can also decide how to handle radio use (or if talking into radios even
applies to their mob type).
Allows properly keyed headsets to broadcast in robot talk and/or hivemind

Adds :0 speech code which activates radio-defined behaviour.
Removes unused radio code, world print in forcesay
Added goddamn atrocious wig for Earthcrusher.
Merge pull request #6671 from Zuhayr/finiwig

Added goddamn atrocious wig for Earthcrusher.
Merge pull request #6681 from Baystation12/dev-freeze

Dev freeze -> Dev
Makes the number of load/storable character slots a configurable value.
Merge pull request #6711 from PsiOmegaDelta/SlotConfig

Configurable number of character slots
Space icon
Map additions

The lazy captain now has another button to control the starboard bridge doors.
Adds a newscaster to the AI core.
Makes sub-sub-grid cables cyan.
Ensures that the cables of the department subnet "flow" from the substation, making it easier to follow the cables towards the power source.
Merge remote-tracking branch 'upstream/master' into dev

Conflicts:
	code/ATMOSPHERICS/pipes.dm
	icons/atmos/pipes.dmi
Merge pull request #6721 from PsiOmegaDelta/LazyCaptain

Map changes
Merge branch 'master' of https://github.com/Baystation12/Baystation12 into dev-freeze
Merge pull request #6730 from Zuhayr/dev

Dev
Less PDA confusion.

When writing PDA messages the input window title is now that of the receiver's PDA name instead of the sender's.
Cable redundancy.

Extra wiring redundancy in the civilian sections, complementing what's already been done in other areas.
Results in maintenance tunnels becoming about as busy they deserve to be.
Merge pull request #6749 from Baystation12/master

Master -> Freeze
Merge pull request #6750 from Baystation12/dev-freeze

Dev freeze -> Dev
Merge pull request #6738 from PsiOmegaDelta/Messaging

Less PDA confusion.
Merge pull request #6743 from PsiOmegaDelta/Wires

Cable redundancy.