Tweak hog steering

* mods/ENTITIES/mcl_mobs/api.lua (on_step): Call
expel_underwater_drivers when not should_drive.

* mods/ENTITIES/mcl_mobs/mount.lua (expel_underwater_drivers):
New function.

* mods/ENTITIES/mobs_mc/pig.lua (on_rightclick): Configure
suitable attachment offsets before attaching riders.

mods/ENTITIES/mcl_mobs/api.lua

@@ -461,6 +461,9 @@ function mob_class:on_step(dtime, moveresult)
 
 	   self:check_breeding()
 	   self:check_aggro(dtime)
+
+	   -- Expel drivers riding submerged mobs.
+	   self:expel_underwater_drivers ()
 	end
 
 	if self.do_custom then

mods/ENTITIES/mcl_mobs/mount.lua

@@ -132,6 +132,19 @@ function mob_class:should_drive ()
 	end
 end
 
+function mob_class:expel_underwater_drivers ()
+	-- Detach the driver if submerged.
+	if self.driver then
+		local headin = minetest.registered_nodes[self.head_in]
+
+		if headin.groups.water then
+			force_detach (self.driver)
+			self:roam ()
+			return
+		end
+	end
+end
+
 function mob_class:drive(moving_anim, stand_anim, can_fly, dtime, moveresult)
    if self.steer_class == "controls" then
 	   self:drive_controls (moving_anim, stand_anim, can_fly, dtime, moveresult)

mods/ENTITIES/mobs_mc/pig.lua

@@ -67,7 +67,6 @@ mcl_mobs.register_mob("mobs_mc:pig", {
 		 return true
 	end,
 	on_die = function(self)
-
 		-- drop saddle when horse is killed while riding
 		-- also detach from horse properly
 		if self.driver then
@@ -148,9 +147,17 @@ mcl_mobs.register_mob("mobs_mc:pig", {
 			return
 
 		elseif not self.driver and self.saddle == "yes" then
-			-- Ride pig if it has a saddle
+			-- Initialize attachment properties.
+			if not self.v3 then
+				local vsize = self.object:get_properties ().visual_size
+				self.driver_attach_at = {x = 0.0, y = 6.5, z = -3.75}
+				self.driver_eye_offset = {x = 0, y = 3, z = 0}
+				self.driver_scale = {x = 1/vsize.x, y = 1/vsize.y}
+				self.v3 = 0
+			end
 
-			self:attach(clicker)
+			-- Ride pig if it has a saddle
+			self:attach (clicker)
 			return
 		end
 	end,