virus fixes.  WIP will update commit message later

Signed-off-by: Mloc-Argent <colmohici@gmail.com>
Bumped infection chance so viruses infect.
Merge branch 'virofixes' into viro
Adds contact-spread viruses.
Infection chance now calculated differently for airborne and contact ones.

Contact viruses spread on: infected people touching others, people touching naked infected people (clothed parts do not spread it).
Airborne viruses spread on: breathing (20% chance, then chance depending on worn clothing), coughing (now 2 tiles instead of 1)

Both types spread from mucous and blood puddles because lazy.

Fixes:
Blood and mucus now spread viruses correctly.
Lowered output of hyperzine generation syndrome, since it caused dedly ODs.
Changes to Shutdown Syndrome.
Now it only affects limbs.
Icon is changed to deformed to reflect it.
Dead limbs do not cause pain messages.
Merge branch 'dev' of https://github.com/Baystation12/Baystation12 into viro
Changelog
Lowered immunity chance, it fires way too often with multiple viruses and such.
Merge branch 'viro' of https://github.com/Mloc/Baystation12 into viro

Conflicts:
	code/modules/virus2/disease2.dm
	code/modules/virus2/effect.dm
Merge branch 'dev' of https://github.com/Baystation12/Baystation12 into viro
No idea why, but it caused all mobs spawn with deformed limbs.
Merge branch 'dev' of https://github.com/Baystation12/Baystation12 into viro
Merge pull request #3731 from comma/viro

Viro