New font colors for mixed (positive/negative) traits and threshold traits

This adds two more colors to the list of traits in the player “window”, in order to make it a little bit more readable, aside from the current colors green (positive trait), yellow (neutral/indifferent trait) and red (negative trait).

a) Threshold traits/mutations are shown in white color.
b) Traits which have positive as well as negative effects are now shown in pink color.
Note this differs from neutral (“yellow”) traits which have no or very little effects.

In order to enable b), a new variable for traits has been added: mixed_effect.
This is a boolean which, if true, declares a trait having positive and negative effects.
The “default” procedure of selecting green/red/yellow color based on its points value is ignored then. This is purely declarative and only used for the player window (at the moment).

A very brief documentation is provided in JSON_INFO.md.

The following traits count as mixed:
* Tentacle Arms
* Tentacle Rakes
* Leg Tentakles
* Tentacle Bracing
* Ectothermic
* Growling Voice
* Hissing Voice
* Snarling Voice
* Hooves
* Curled Horns
* Pointed Horns
* Huge
* Freakishly Huge
* Inconveniently Large
* Large Talons
* Mandibles
* Lupine Muzzle
* Ursine Muzzle
* Reptilian Muzzle
* Paws
* Saber Teeth
* Chitinous Armor
* Genetically Unstable
* Hollow Bone
* Antlers
* Beak
* Rubbery Limbs (BENDY2)
* Rubbery Limbs (BENDY3)
* Bovine Snout
* Toe Talons
* Shell
* Thick Scales

If you know any other trait I’ve forget, please tell me! I am not sure if I should add Mood Swings.