Add modRana icons in various sizes

So that they are present in the tarball and can be easily grabbed
by a specfile or equivalent when build a modRana package.
Make it possible to load the theme config file from qrc

This makes it possible to skip extracting the theme files on
Android (loading of icons from qrc is already supported),
saving about ~6 MB of installed size space.
Creating the themes folder is no longer needed

As we don't need to export the themes folder content.