Added a main page for the Doxygen documentation

Tweak the settings a little too, include the version number.

Change-Id: I77117810d5eb64ef1d7e0b12ac95e556f76991f5
Added README.md, CONTRIBUTING.md, install and update

Added some standard documentation files, make sure the COPYING file is
installed along with the documentation.

Change-Id: Iba7ccfb30920feb31fb6e6c6e00e392feb695c38
Merge branch 'documentation'

Change-Id: I1a22ec1480634da1f607d7511a8669c427a08faf