BUG: Fix a typo

This commit fixes the following error:

 PHP Notice:  Undefined variable: coveragestatus in
 /var/www/cdash/ajax/getviewcoverage.php on line 299
ENH: Support PostgreSQL in filter data functions

Tested-by: Nils Gladitz <nilsgladitz@gmail.com>
BUG: Fix undefined variable usage in test viewer.

This commit fixes the following issue:

  PHP Notice:  Undefined variable: extras in /var/www/cdash/viewTest.php on line 273,
  referer: http://localhost/cdash/viewTest.php?buildid=391
ENH: Add menu to viewNotes page

Also drop some unused variables; Move <pre> tags outside of <p> tag;
BUG: Generate xhtml to make markdown standard compliant