Some polishing touches for VisualUnitTest

* Fix spacing in URL links in MiniHTML class.
* Fix HTML validation warnings.
* Clean up; removal of dead code, clean up of headers.

* Update documentation for VisualUnitTest; credit Riley Adams for
the implementation.
* Add LICENSE file for VisualUnitTest; portions copyright Ogre3D.
* Add copy of results.js & results.css in Resources/tests/VisualUnitTest.