Tree API: Automatic creation of growing functions (with schematic)

[lnjX]

Now you can give default.register_tree a schematic and it creates a function for it.

Here are some examples:

default.register_tree("default:apple_tree", {
    schematic = core.get_modpath("default") .. "/schematics/apple_tree_from_sapling.mts",
    schematic_size = {x = 2, y = 1, z = 2},
    sapling = {
        growing_type = "schematic_and_function",
        mgv6_grow = function(pos)
            if not default.can_grow() then
                return false
            end

            return default.grow_apple_tree(pos, math.random(1, 4) == 1)
        end,
    }
})

default.register_tree("default:acacia", {
    schematic = core.get_modpath("default") .. "/schematics/acacia_tree_from_sapling.mts",
    schematic_size = {x = 2, y = 1, z = 2},
    sapling = {
        growing_type = "schematic",
    }
})

[lnjX]

@JBBgameich If you don't have any improvements, you can merge it.