Fix some PHP Notices when visting the Manage Ratings admin page
Use $postratings_filterrating variable instead of $_GET
Fix PHP notices on Options & Templates admin screens.

$text_direction referred to a global variable which wasn't in scope.
Switch to use is_rtl() instead.
Fix PHP Notice when going to Uninstall screen
Merge pull request #2 from paulgibbs/debug_fixes

Fixes for PHP Notices. Props paulgibbs.