Fix tabs and jQuery 1.9 compatibility
- Replace .toggle( max, min ) (deprecated); minor tweaks to showHideButton element
- Use jQuery UI collapsible support, rather than manual show/hide, which was causing bugs; rename tabs element.
- Use beforeActivate instead of show so there's no flash
- Replace events for clicks on tab links with handling in beforeActivate. Also move logic to update up/down show/hide button here, required for consistent state.
- Change terminology to match jQuery UI Tabs.
- Refactor template/dummy element creation to keep tabs element clean.
Fixes issue #187 and issue #189.