Happy Ghast Rework

This is a mod aimed at reworking the Happy Ghast in order to turn it into a viable, vanilla-friendly mount.

Consult the chart below for the changes this mod introduces:

20 HP → 40 HP.

0.05 movement speed → 0.08 movement speed (60% speed increase).

Immunity to fire/lava hazards (Hostile Ghast and Blaze projectile attacks will still deal damage, but will not cause the Happy Ghast to remain on fire).

Snowballs can now be used to heal 25% of the Happy Ghast's HP.

When not being ridden by a player, the Happy Ghast will slowly descend and remain hovering close to the ground, allowing the Ghast to always remain within the player's reach.

UPDATE v1.1.0:

Happy Ghasts are now able to shoot fireballs out of their mouths, they have a meter/gauge that allows them to hold up to 16 fireball charges at any one time. Press right-click while riding to fire one, each shot has a 2.5 second cooldown between the other.
Due to its huge size, enemies will now be able to spot you from 40m away instead of the usual 16m while riding the Ghast.
Feeding it a Snowball will restore 4 HP instead of the old 10 HP and will restore no Fireball charges.
Feeding it a Fire Charge will restore 5 charges.
Feeding it a Ghast Tear will restore 3 charges and 6 HP.
Feeding it a Phantom Membrane will restore 12 HP and 2 charges over the span of 15 seconds.
Hover-to-ground behavior was removed due to being considered too redundant and clashing too much with the Ghast's flight AI.
Playing a Goat Horn will cause every Happy Ghast within a 120m radius to flight path to the source of the sound.
When a player is riding a Happy Ghast, both ground enemies and ranged enemies will prioritize taking down the Happy Ghast over the player, aggro will remain on the Ghast even after being unmounted.
If you don't like or disagree with any of these changes and/or values, the mod has been made to be (almost) completely configurable from the options menu.

UPDATE v1.1.1:
Happy Ghast now uses Sneak Key to descend, Sprint Key is used to dismount instead, can be enabled or disabled from the config menu.

UPDATE v1.1.2:

Happy Ghasts can now be overfed fireball charges once fully topped, each unit of fireball multiplies the next Fireball blast's explosive power by 0.20x up to a limit of 10x the original blast size, can be fully configured and disabled in the mod manager. 
Previously broken configuration options have been fixed to properly function inside the game.
Happy Ghast's Fireball meter will persist on the player's screen for 3 seconds after dismounting it.

Snowball's lure distance has been increased from 16m to 24m, fully configurable in mod manager.

Leashed Happy Ghasts and Happy Ghasts not wearing Harnesses will now ignore the Goat Horn's call.
Happy Ghasts will stand still for 3 seconds after arriving to the Goat Horn's location.

Happy Ghasts will give up going after the Goat Horn's source if they haven't reached the target area within 60 seconds.

UPDATE v1.2.0:

The ghast now possesses a moisture bar, it can be refilled by feeding the Happy Ghast water buckets, snowballs, blocks of ice, or submerging it in water/rain/snow, it will go down 1.5x faster when inside the Nether due to the dimension's higher temperature, the more the moisture bar decreases, your ghast will start to turn greyer, sadder and weaker until it eventually reaches 0% and becomes extremely weak (-50% move speed, +100% damage taken) and vulnerable to fire/lava again, but if it dies while in this state it will turn back into a dried ghast.

Buffed Phantom Membrane's overtime effects to take effect much faster (15 seconds → 4 seconds).

Nerfed Snowball from 4 HP to 3 HP, will not heal unless Happy Ghast's moisture bar is full.

Dried Ghast's spawn rate in the Nether fossils has been decreased from 30% to 12% (can be configured to your liking).

The Happy Ghast swimming on lava/fire will very quickly decrease it's Moisture bar, so try to stay away from fire hazards.

Added SFX for when you feed the Happy Ghast an item.

Added an option to invert the descend/leave ride controls.

Happy Ghasts can now feed on Warped Fungus, each one will restore 5% moisture and 4 HP.

As usual, almost everything can be configured or disabled, so you're not stuck with the pre-defined values.

UPDATE v1.2.0.1:

Changed some default values on the moisture mechanic.

Added missing configuration options.

UPDATE v1.2.0.1.2:

Fixed incorrect icon resolution.