Make metabolic mutations more interesting

[Coolthulhu]

Changed two really bad mutation lines into something worth considering keeping:
Fast metabolism mutation line gains a boost to stamina regeneration:

Metabolism	Bonus stamina regen
Fast	10%
V. Fast	30%
Extreme	50%

This bonus is applied even during "winded" effect, unlike regular human stamina regeneration.
However it does not skip penalties for mouth encumbrance - can't really fuel that super metabolism without oxygen. This sets it apart from the bionic, which works regardless of masks.

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Cold blooded line gains low metabolism. After all, not maintaining body temperature means less work to stay alive.
The lowest level cold blooded becomes as effective as Light Eater (33% less food). All above it become even better: 50%.

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Also some minor, moderately related changes:

• Prevented application of Winded status for characters above 50% stamina. It was kind of jarring to see characters become winded after taking 2-3 steps.
• High thirst mutation line becomes less rewarding in points. Water is plentiful, it literally falls from the sky.
• Recycler bionic stops working as well with mutations. It was made with normal humans in mind, not hyper-metabolic mutants. It stops scaling with high metabolism and stops stacking with slow metabolism.

[codemime]

Could be replaced with clamp() from cata_utility.h.

[Coolthulhu]

The problem is, the maximum value changes too.
Clamp expects min <= max, which can't be guaranteed here: hunger_rate - 0.5 can be above or below 0.5.

[BevapDin]

This ternary with the negated condition is slightly confusing. It would be cleared without the negation (and inverted results) as has_effect() ? 0 : 1.