export apply_bone_meal function in mcl_dye

this is essentially just a hack to not put any more sweetberry code
in mcl_dye because the architecture makes it necessary for mcl_dye
to depend on mcl_farming, not the other way around - hence all the
plant bonemealing is done in mcl_dye...

mods/ITEMS/mcl_dye/init.lua

@@ -379,6 +379,8 @@ local function apply_bone_meal(pointed_thing,user)
 	return false
 end
 
+mcl_dye.apply_bone_meal = apply_bone_meal
+
 minetest.register_craftitem("mcl_dye:white", {
 	inventory_image = "mcl_dye_white.png",
 	description = S("Bone Meal"),