panels 6.x-3.1

This is primarily a bug fix release for Panels.

Important!!!!!!!
You must upgrade Chaos Tool Suite (CTools) to 1.1 when upgrading to Panels 3.1! This is NOT optional! If you do not do this, your panels will deactivate themselves.

• #552846 by eMPee584: Fix notice with tablesorts on mini panels page if no mini panels exist.
• #568218: Links to clone, export, delete/revert, enable/disable variants from the main summary page were incorrect and led to an operation trail not found message.
• #533724: Prevent Panels from upgrading while uninstalled, as that upgrades into broken pages.
• #529816: Allow flexible layout to add custom classes to each region.
• Rearrange the pane dropdown menus to be better organized and look a little nicer.
• Add a new field to allow setting a panel title from one of its panes.
• #562560 by Damien McKenna: Integration with export.module
• #583172 by jacine: Turn panel pane into a template, as it always should have been.
• #604404: Make sure caching does not trigger for form POSTs.