Various improvements to the footer columns

* Moved logo from the header to the right footer column
* Removed unused classes from footer
* Add messages for optional extra content in footer columns;
  erudite-extracontent-column{1,2,3}
* Removed newpages content (not generally useful and difficult
  to make fast)
* Re-organised footer content:
  * column 1: search, other languages (if available), personal tools
  * column 2: toolbox
  * column 3: logo
(updated change to update #logo css appropriately)

Change-Id: I0ea7ee498948fa0ff22ad78669ff33656d9f40e4
Merge "Various improvements to the footer columns"