Cephalopod branching

Nothing hugely special, just gives Cephalopds some separate traits (the
eyes include Nicitating Membrane & Bulging, and the vision is pretty
much FNV with extra Glare penalties).
Rat love

Improves Rat branching (muzzle, broke out whiskers, new claws, condensed
metabolism) and provides some higher-end mutations for 'em (nastier
claws, bite, burrowing).

Capstone post-thresh payoff ATM is being able to eat through walls, no
pickaxe required.

Thanks to Rivet for helping sound out the wall-breacher.
Lizard limb-regen

Benefit to one of the first post-thresh categories: if you splint your
broken limb, its chance of recovery is 20x faster than normal.  If you
*don't* splint it, you still get some chance, just the typical two-week
period.
Fix typo.  Thanks, Lain.
Added description for BELTED, OUTER and FLOATATION
Rephrased
Timechecks!
Belted description
Fix strings.
OUTER description
Added as else-if block
Added description for default layer items
Merge pull request #9714 from KA101/muts

Pre 0.B mutations
On cruise faster/slower, where safe_velocity used to be skipped, is now
given as cruise target speed.
Fix MUZZLE_RAT
Revert "Added sewage as a water source for crafting"

This reverts commit 33ad52fe73b8cae79616f8fbd8e652cabd304d4f.
Replaced custom value of max_vel with max_velocity()
Functionality works with reverse and max vehicle speed
Merge pull request #9758 from KA101/mutfix

Fix MUZZLE_RAT
Merge pull request #9759 from kevingranade/revert-sewage-water

Revert "Added sewage as a water source for crafting"
Strain check returns non-zero result when velocity is negative and over
safe velocity