Better layout for the Hooks panel
Remove unnecessary SPL check
Alter the `is_ajax()` method so it only returns true for proper WordPress AJAX requests
Switch to `ob_end_flush()` to prevent QM's output being buffered and causing various errors. Fixes issues with W3TC and other plugins that use output buffering. See #26.
Simplify some code when we're forcing QM to the front of the list of active plugins