Opt in folders

[graphius]

by default all folders are scanned for images, including icons, templates, etc

Instead of putting a .nomedia file in every folder I want to exclude, and remembering to add the file if I create any new root folders, it would be nice to have an interface to only add specific folders. Maybe with an option to include all, or include new folders.

[haklc]

I'm also in favor of this over all other options.

[6lv1-blr]

Also agreed with that

[joshtrichards]

Duplicate of #141. Please consolidate votes/comments there and close this Issue so that interest is clearly noted rather than spread out and diluted. :)