Add Ghoat and update warthog/pumba

- The Ghoat animal is passive, he eats flowers on his way, drop raw_meat if you kill it. But be carful, if you attack him, he will hit you back ! (like cow/warthog and other passive monster who can defend himself)
- Warthogs now spawn on default:dirt and default:junglegrass, this change is made because we move progressively the warthog in jungle

mods/mobs/cow.lua

@@ -9,7 +9,7 @@ mobs:register_mob("mobs:cow", {
 	attack_type = "dogfight",
 	damage = 5,
 	-- health & armor
-	hp_min = 20,
+	hp_min = 25,
 	hp_max = 30,
 	armor = 200,
 	-- textures and model

mods/mobs/init.lua

@@ -12,6 +12,7 @@ dofile(minetest.get_modpath("mobs").."/warthog.lua") -- KrupnoPavel
 dofile(minetest.get_modpath("mobs").."/bee.lua") -- KrupnoPavel
 dofile(minetest.get_modpath("mobs").."/bunny.lua") -- ExeterDad
 dofile(minetest.get_modpath("mobs").."/kitten.lua") -- Jordach/BFD
+dofile(minetest.get_modpath("mobs").."/ghoat.lua") -- ???
 
 -- Monsters
 
@@ -28,6 +29,8 @@ dofile(minetest.get_modpath("mobs").."/mese_monster.lua") -- Zeg9
 dofile(minetest.get_modpath("mobs").."/spider.lua") -- AspireMint
 dofile(minetest.get_modpath("mobs").."/greenslimes.lua") -- davedevils/TomasJLuis/TenPlus1
 dofile(minetest.get_modpath("mobs").."/lavaslimes.lua") -- davedevils/TomasJLuis/TenPlus1
+dofile(minetest.get_modpath("mobs").."/zombie.lua") -- ???
+
 
 -- begin slimes mobs compatibility changes
 -- cannot find mesecons?, craft glue instead

mods/mobs/sheep.lua

@@ -29,6 +29,7 @@ mobs:register_mob("mobs:sheep", {
 	},
 	-- speed and jump
 	walk_velocity = 1,
+	run_velocity = 2,
 	jump = true,
 	-- drops raw meat when dead
 	drops = {

mods/mobs/warthog.lua

@@ -86,8 +86,8 @@ mobs:register_mob("mobs:pumba", {
 		end
 	end,
 })
--- spawns on normal or shroom dirt, between 8 and 20 light, 1 in 10000 chance, 1 in area up to 31000 in height
-mobs:register_spawn("mobs:pumba", {"default:dirt_with_grass", "default:dirt"}, 20, 8, 10000, 1, 31000)
+-- spawns on dirt or junglegrass, between 8 and 20 light, 1 in 10000 chance, 1 in area up to 31000 in height
+mobs:register_spawn("mobs:pumba", {"default:dirt", "default:junglegrass"}, 20, 8, 10000, 1, 31000)
 -- register spawn egg
 mobs:register_egg("mobs:pumba", "Warthog", "wool_pink.png", 1)