i18n: Updated i18n strings
Menu: Changed menu panel heading, button and title to 'Search and menus'
 Menu: Added search icon to mobile panel button and increased mobile panel button height by 20%
Template:  Changed heading text and skip link text for site menu, secondary menu and site information
Menu: Fixed outlining of non-section wb-navcurr links in the menu panel
Merge pull request #5703 from pjackson28/fixesusability

Usability: Template and menu plugin fixes to address usability testing results