Add _vl_projectile.can_punch() to mob API and move hard-coded entity behavior from arrow to rover code

mods/ENTITIES/mcl_mobs/api.txt

@@ -265,6 +265,8 @@ functions needed for the mob to work properly which contains the following:
     'attack_frequency'  Attack frequency in seconds. If unset, this defaults to 1. Implemented for melee only atm.
 
 	mobs:gopath(self,target,callback_arrived)		pathfind a way to target and run callback on arrival
+	'_vl_projectile'	Table with Projectile API behaviors. Current members are:
+		'can_punch(self, projectile_luaentity)' return 'false' from this function to prevent the provided projectile from colliding with the mob
 
 
 

mods/ENTITIES/mcl_mobs/init.lua

@@ -286,6 +286,7 @@ function mcl_mobs.register_mob(name, def)
 		noyaw = def.noyaw or false,
 		particlespawners = def.particlespawners,
 		spawn_check = def.spawn_check,
+		_vl_projectile = def._vl_projectile,
 		-- End of MCL2 extensions
 		on_spawn = def.on_spawn,
 		on_blast = def.on_blast or function(self,damage)

mods/ENTITIES/mobs_mc/rover.lua

@@ -147,6 +147,9 @@ mcl_mobs.register_mob("mobs_mc:rover", {
 		max = 1,
 		looting = "common"},
 	},
+	_vl_projectile = {
+		can_punch = function() return false end
+	},
 	animation = select_rover_animation("normal"),
 	_taken_node = "",
 	can_spawn = function(pos)

mods/ITEMS/mcl_bows/arrow.lua

@@ -87,12 +87,6 @@ local arrow_entity = {
 			vl_projectile.collides_with_solids,
 			vl_projectile.raycast_collides_with_entities,
 		},
-		allow_punching = function(self, entity_def, projectile_def, object)
-			local lua = object:get_luaentity()
-			if lua and lua.name == "mobs_mc:rover" then return false end
-
-			return true
-		end,
 		sounds = {
 			on_entity_collision = function(self, _, _, _, obj)
 				if obj:is_player() then

mods/ITEMS/vl_projectile/init.lua

@@ -469,6 +469,12 @@ local function handle_entity_collision(self, entity_def, projectile_def, object)
 	local dir = vector.normalize(self.object:get_velocity())
 	local object_lua = object:get_luaentity()
 
+	-- Allow entities to selectively prevent being hit
+	local entity_hook = object_lua and object_lua._vl_projectile and object_lua._vl_projectile.can_punch
+	if entity_hook and entity_hook(object_lua, self) == false then
+		return
+	end
+
 	-- Normally objects should be removed on collision with entities
 	local survive_collision = projectile_def.survive_collision