Don't search in scripts or shaders directories for "Select directories you wish to add" menu in launcher

When appending a new data directory in the launcher, when the Select directories you wish to add menu pops up, it will show scripts and shaders directories as options, because they will often have nested textures or animations directories. I believe this is undesirable, as a user will never want to just add scripts or shaders, as they won't work standalone. They also clutter up the menu.

Example: