More robust AJAX stuff that will eliminate some ugly errors plus prevent double clicks on ajax links.

Initial commit of content API into ctools. Only one content type is ported, but there are some docs.

Retool the access plugins to allow multiple plugins plus and/or switch. Retool selection criteria to use this allowing for a much richer selection of task handlers on a given page.

A tool to facilitate multi-step wizards. I do not think this is quite finished yet but it handles the simple case pretty well.

- a tool for AJAX, which is the next generation tool based on what Views uses.
- a tool for modals -- completely ripping the modal out of Panels.
- moving plugins for 'arguments', 'relationships' and 'contexts' into CTools.

Add callbacks to the collapsible so that it can be trivially transformed into other things like an accordion. Add accordion functionality to the task admin UI.