Revert "Solve #182 add table pool for events"

This reverts commit dff522fbaa.

druid/base/static_grid.lua

@@ -115,16 +115,6 @@ function StaticGrid.init(self, parent, element, in_row)
 end
 
 
-function StaticGrid.on_internal_remove(self)
-	component.on_internal_remove(self)
-	self.on_add_item:clear()
-	self.on_remove_item:clear()
-	self.on_change_items:clear()
-	self.on_clear:clear()
-	self.on_update_positions:clear()
-end
-
-
 local _temp_pos = vmath.vector3(0)
 --- Return pos for grid node index
 -- @tparam StaticGrid self @{StaticGrid}