Fix #977: util/misc.escapeCssId: Ensure parameter is string
Fix #765: _StoreMixin: Show noDataMessage when store is null
Fix #848: Pagination: Improve focus-related logic for navigation

* Set tabIndex to -1 on disabled navigation links
* Restore focus accordingly based on what was focused and what is now disabled
Cleanup of earlier commits today
Fix a typo
Merge branch 'master' into dev-0.4

Conflicts:
	extensions/Pagination.js