Class-hierarchy for mobs

[bell07]

At the first I really like the class based structure of this mod. But currently just the functionality is grouped to classes. I miss the Class-hierarchy of the Mob-Classes. Currently there is just one Mobs-Class named "ai_library" that is copied to all defined mobs and does have all the logic. I see you run into problems because there is no "universal" logic possible. The result are many not needed if's like "if jumper then, elseif aqua, then, elseif ridable then .... I tried to fix a issue with NPC after stop walking, because freezing of the walk-animation seems strange for NPC. Then I realized the freeze is fine for cows or horses, and allways enable the stay-animation will be seems strange for this npc types.
I'm not a OO-guru, but I imagine it as follows (some pseudo-code):

-- base-class that contains just the really universal minimum (framework and luaEntity related things)
ai_base = {}

Then the hierarchy
ai_animal = table.copy(ai_base)
ai_animal.animation = animal_specific_animation

ai_monster = table.copy(ai_animal)
--have same animation

ai_npc = table.copy(ai_animal)
ai_animal.animation = npc_specific_animation

Now there is no mix with the many ifs. Each method is assigned to the right class.

Of course we need a registration, like "register_ai("type", class)" that register the usable classes in a table.
ea_table["npc"] = ai_npc

The "register_mob" can get the mob_type = "npc" in interface to select the right implementation.

If the "register_ai" is available for other mods it is possible easy to add new mobs from other mods

A second advantage of multiple more specific classes is: the classes can contain usable defaults so the register_mob() parameters list can be reduced. A sample: the NPC does have allways the visual = "mesh" with mesh = "character.b3d" and allways the same collisionbox and radius...