[MoM] Psi equation fixes

[Standing-Storm]

Summary

Mods "[MoM] Psi equation fixes"

Purpose of change

I made a mistake in the equation--in order to prevent the psi equation from influencing the magic equation, I took out the cap for psi_effective_skill. Unfortunately, that led to very strange behavior, since when effective skill was above 30 it stated to come back down the other side of the convex function. And it didn't even work, since when it hit 30 effective skill by Magiclysm's formula it suddenly snapped to zero.

Describe the solution

Re-work the formula slightly so that powers with the PSIONIC flag check up to 40 effective skill instead of 30:

if( ( effective_skill > 30.0f && !has_flag(spell_flag::PSIONIC ) ) || ( psi_effective_skill > 40.0f && has_flag(spell_flag::PSIONIC ) ) )

This makes sure that magic follows the magic formula and psi follows the psi formula, and it also gives psi more room to breathe so that focus can take effect--previously it was very easy to hit the 30 effectiveness skill cap and jump straight to "no failure chance" since focus calculations take place further down the function.

I also went through and added "skill": "metaphysics" to every power that was missing it.

Describe alternatives you've considered

Testing

At metaphysics 0 with high focus, fail chance is a coinflip. At metaphysics 0 with low focus, powers are unusable. That's fine with me--this is the equivalent of attacking a zombie with melee skill 0 at high stamina and low stamina. Train your skills if you want to be successful.

At metaphysics 6 with high focus, fail chance is basically nil. At metaphysics 6 with low focus, fail chance ranged from 5% to 20% depending on power level.

At metaphysics 10, low-Difficulty powers always succeeded even at low focus and even at extremely high (500+) levels of pain reducing Intelligence to 0. Even high-Difficulty powers only had a 20% failure chance.

(I might want to do something with flags or something to make pain itself have an effect on psi above and beyond loss of intelligence, since even Professor X would have trouble if all of his limbs were broken and he was suffering from arterial bleeding, but that's out of scope for this PR)

At no point did I witness higher skill or power level causing an increase in failure chance.

Additional context

Lesson to self--always test with a slime mutant.