themes are incomplete in rails-5-2

[cpg]

themes are now:

• residing in public/themes
• their init.rb is the same, however, there is no interpretation on assets, they have to be compiled
• created an src folder with the style.scss, _mixins.scss, then generated the css with by compilind the scss by hand.
• there is no asset pipeline involved
• app themes will NOT work, as they install in app/assets/ iirc.