Improve responsive design (search form, table) and menu button

* Search form: invert position of search field and search options, improve design on small resolutions, especially under 480px.
* Tables: display labels when table items are collapsed (if class="collapsable"), don't collapse tables without class
* Menu tile: center Transvision title and experimental view notice, move menu to the right and use a smaller image for large resolutions (125x75 vs 150x90) and a tiny one for under 480px (100x60px) to avoid overlappings
* Add padding on credits and changelog, fix typos in changelog, add new/exp tags for new/experimental features
Merge pull request #165 from flodolo/fix_responsive

Improve responsive design (search form, table) and menu button