Removed unnecessary noise during the effect of the "Mana drain" spell in place of its creation.
The player's armor class, magic resistance, poison resistance and inflicted damage now depend on buffed attributes and skills instead of base ones.
The player's critical strike chance now depends on values set in melee weaponry scripts (SETEQUIP CRITICAL) and is properly affected by the words of power.
Remove unused variable

Was made obsolete in previous commit.
Remove trailing whitespace
Return 0 from ARX_EQUIPMENT_Apply*() on error

Returning the full base value makes no sense as these functions
calculate a *delta* to be added to the base value!
Remove trueval param from ARX_EQUIPMENT_Apply()

Wasn't used (anymore).
Remove entity param for ARX_EQUIPMENT_Apply*()

These were always called on entities.player() anyway and didn't do
anything for non-player entities.
Merge ARX_EQUIPMENT_Apply*() implementations
Rename ARX_EQUIPMENT_Apply()

... to getEquipmentBaseModifier().
Add a function for the total equipment modifier
Use getEquipmentModifier() for attributes
Use getEquipmentModifier() for skills
Use getEquipmentModifier() for other stats
Remove ARX_PLAYER_Get_Skill_*() functions

Move calculations into ARX_PLAYER_ComputePlayer*Stats().
Remove ARX_EQUIPMENT_ApplyPercent()

Wasn't used (anymore).
Calculate spell/skill modifiers earlier
Add helper variables for attribute calculation
Add helper vars for calculation of other stats
Use up to date attributes to calculate other stats