If the selection is on the cell level and the selectionMode is extended, clear the selection if a modifier key was not pressed.
Merge branch 'cellselection' of git://github.com/SitePenMatthewMaxwell/dgrid into cell-selection-rclick
Revise Selection right-click logic to avoid issues with Lists
Document CellSelection right-click fix in CHANGES.md
Fix #379: change Pagination links to spans; avoid IE9+ dispatchEvent bug

This led to a few other changes as a result, to ensure equivalent
functionality as before:

* Added "dgrid-page-link" class to all clickable nodes in the navigation area
* Added tabIndex to all nodes that were formerly `a` tags, so that they are
  still keyboard-navigable
* Added keyboard handling to all nodes that were formerly `a` tags, so that
  enter still fires their actions
* Removed IE<8 CSS that is no longer needed
Document Pagination changes for IE9+ dispatchEvent fix in CHANGES.md