Fix texture modifiers relying on undocumented behavior
modlib
now has a texture modifier parser so I decided to run that against the texture modifiers in various games (see also https://git.minetest.land/MineClone2/MineClone2/pulls/3761). You have two [opacity
modifiers with an extraneous closing ]
bracket, probably due to automatic bracket matching in your editor. This PR fixes that.