FS#2221 Merge frontend improvements

CSS, XHTML, JS, Browsers

• 

  2011-04-16 andi

  The discussed changes to the Frontent HTML code stored at https://github.com/splitbrain/dokuwiki/tree/frontend_improvements should be merged into the master tree.
• 

  2011-05-15 ach

  As there are not many things in that branch, the primary task is to first actually *do* some of the discussed improvements, before it can get merged into master. ;-)
• 

  2012-04-10 ach

  As that branch was very old, I deleted it and created a new one with the same name. I finally also managed to get some more stuff done and opened a pull request: https://github.com/splitbrain/dokuwiki/pull/93
• Related tasks:
  • FS#1351 xhtml strictness for images and removing redundancy
  • FS#2213 Remove unnecessary attributes to enable HTML5 doctype in templates