Delete the old ui entirely

We can't keep maintaining 2 UIs so the old one has got to go.

This will be a pain for our translators as there are now a ton of untranslated new strings, but that's just the way it is.

I expect this to be the last big "language breaking" change. There will of course be new strings in the future though.

I also hope to reduce the number of strings a bit in the future by changing some things to little icons but only a few things are suited for that, like Grid/List in the new game list.