Moves mutantraces to datums

After a long two weeks of work, I have moved every mutantrace (as well
as humans) to /datum/species. As datums, the code is a lot less
scattered and cluttered. The species datums have many procs and vars
which handle the different aspects of the various mutantraces. The list
is too extensive to put here, but I have tried explaining everything as
well as I can in comments in the code.

This also has the mutant colors I was working on earlier - certain
species can have customizable skincolors. This is done by changing the
'alien color' setting in your preferences. At the moment, the only
species that use mutantcolor are lizardpeople, slimepeople,
pod/plantpeople, and jellypeople. This is now a config option, which
defaults to 'off'. If turned off, those species will use their default
color.

Some other small changes: medical scanners now display your species,
golems no longer have blood, plantpeople are vulnerable to heat and
fire, shadowpeople will not be targeted by Faithless anymore, your
species is displayed on the player preferences panel.

As a side note: I am working on removing the invisible adamantine golem
armor. I have basically moved all of its functions to the actual golem
datum itself; the armor just exists to prevent golems from wearing
clothing. I plan on integrating clothing settings into the species
datums after this is done. I cannot due them now due to the new
polymorphic inventory code that was merged while I was working on this.
I also wanted to finish the basic stuff first before tackling anything
else.