Used an & in the definition of add_controller, rather than the calls to it.

git-svn-id: http://plugins.svn.wordpress.org/latex-everything/trunk@776084 b8457f37-d9ea-0310-8a92-e5e31aec5664
Version bumped to 1.3.

git-svn-id: http://plugins.svn.wordpress.org/latex-everything/trunk@776091 b8457f37-d9ea-0310-8a92-e5e31aec5664
Added the 1.3 release to the changelog and upgrade notices.
Added a more informative error message when pdflatex and pdftk are not found.
Tested up to Wordpress 3.8.0.
Added notes to readme.txt that the plugin is unsupported.
Merge remote-tracking branch 'origin/master'