Saycode Rework

Created by: N3X15

WIP, have some major bugs to fix still.

CHANGES

• Speech now uses the new /datum/speech for shuttling around speech data.
• Formatting is no longer injected as HTML into the message. HTML will be escaped and presented as normal text. Formatting is kept separate from the message.
• Speech is no longer rendered, encoded, unencoded, filtered, and re-encoded. Characters are left raw and unencoded until they reach someone's ears.
• Saycode logic flow documented. See docs/.
• Mutations and diseases can affect more of the message, including adding and removing classes without parsing HTML.

tl;dr eliminates a lot of the Guy says, "<SPAN!!!" stuff.