* various API functions now work with mobs properly
* the following effects don't work with mobs at all:
water breathing, dolphin's grace, leaping, swiftness,
slowness, slow falling, night vision, darkness, frost,
health boost, absorption, fire resistance, resistance,
luck, bad luck, blindness, nausea, hunger, saturation,
haste, fatigue, conduit power
* the following effects should work with mobs:
invisibility, regeneration, poison, withering,
strength, weakness, levitation, glowing
* the following effects have no effect on mobs
(but can be applied with the API):
bad omen, hero of the village
-heal subcommand to the /effect reimplemented
-healing_func() from old API standardized, included in new API
-(the last point is due to it being substantially different from others)
-fixed a few bugs, potential crashes
-fixed incorrect withering effect progression
-standardized variable naming
-improved the /effect command, allowing to use effect levels
-fixed a bug in level-to-factor conversions
-renamed effect icons to follow the new convention