tweak spider climbing feature

spider.lua

@@ -114,8 +114,8 @@ mobs:register_mob("mobs_monster:spider", {
 		self.spider_timer = 0
 
 		-- need to be stopped to go onwards
-		if get_velocity(self) > 0.2 then
-			self.disable_falling = false
+		if get_velocity(self) > 0.5 then
+			self.disable_falling = nil
 			return
 		end
 
@@ -153,6 +153,7 @@ mobs:register_mob("mobs_monster:spider", {
 		self.disable_falling = true
 
 		-- move up facing
+		v.x = 0 ; v.y = 0
 		v.y = self.jump_height
 		mobs:set_animation(self, "jump")
 		self.object:set_velocity(v)