Migrate .change-locale rules, nix #change-locale

The #change-locale widget does not work correctly in Firefox. Given its
questionable usefulness, it seems more sensible to remove it than spend
much time fixing it. If users want it back, we can revert this commit.
Migrate .description and .translate-display rules
Style pagination correctly in RTL languages

These changes remove the broken .html-rtl rules related to pagination in
wiki-screen, and also updates main/structure.styl with correct rules.
Remove unneeded RTL rules from wiki-screen
Bug 944206: Remove wiki-screen.css
Merge pull request #2377 from openjck/remove-wiki-screen

Remove wiki-screen.css