Remove unused _hasSubs and _hasAfters properties

They are not referenced in the library code, nor did they have API docs.
Build event-custom-base and simpleyui
Allow shift-click from unsorted. Fixes #705
Add tests for #705 shift-click from unsorted
Simplify click vs shift-click logic
Update tests for new sortBy expectation from shift-click
Build datatable-sort
Merge remote-tracking branch 'upstream/dev-3.x' into dev-3.x