Changes the inbuilt loader prototype to be able to stack items on belts (Up to 4) and have a per lane filter.

This does not add any loaders to the game, you must use another mod for that such as AAI Loaders.

It changes these for "loader", "loader-1x1":
l.max_belt_stack_size = 4 -- Default for loader is 1, default for inserters is 4
l.filter_count = 2 -- Default for loader is 5, must be 2 for lane filters to work
l.per_lane_filters = true -- Default is false.