KAM keyboard shortcuts

Although there had been extensive testing of the KAM extension keyboard shortcuts (accessibility#1 (comment 11279)), I'm not sure how extensive it was of the integration into core. This is a list of items that are needed to make the menu accessible according to WCAG 2.0 AA, so far as I can determine from various sites that provide suggestions on implementations for compliant menus, mainklyt WAI tutorials.

• The menu should receive the tab focus first, before other page elements. Currently, one has to tab through other page elements before entering the menu. On wpmaster, it takes 4 tabs, on dmaster it takes 24 tabs in order to get to QuickSearch.
• When focus is in QuickSearch, tab incorrectly moves next to browser address line. It should move forward to the menu item represented by the CiviCRM icon (I don't know its name).

Previous notes from when tabbing worked in the menu:

• When on a menu item with submenu open, space and return as well as escape should close it. Not a priority, but behaviour seems to be non-standard.
• When on an open sub-submenu (eg Contributions > Accounting Batches with Open Batches with focus), using left arrow correctly moved focus to Accounting Batches, but it did not close the sub-submenu. Not a huge priority for usability.