Fix group logic to preserve sort order of rows.
Preserve grid sorting after a flexview refresh
Allow user to sort a grouped column by clicking on the group name.
Primitive use of the group column to sort by groups
Complete group column sorting.
Update grid to show child records - except in case of the hideChildren flag
Misc fixes - show lowest grid level, show all rows, hide lowest level

Commits:
* Fix a bug in how koGrid shows and hides the lowest level in the grid

* Fix a bug in my implementation of show all rows.

* Fix to way grid lowest level was expanded - old implementation resulted in only first row being expand/collapsed

https://app.asana.com/0/3708490240227/7080763879091
Finalize Changes fixes, linenum
Stub in Group Totals
Allow aggregate rows to be selected
Prevent agg cell clicks from affecting selection.
Add (disabled) code to make the group column show line numbers
Add aggregationProvider.js to kogrid
Move lineNum to renderChangeNoGroups
Update extended selection to work with grouping
Add a performance fix to the way row selection is extended.
Stub in cell selection to kogrid.
Add cell selection to koGrid
Add cell selection to aggregate rows.
Add logic to rowFactory.js to clearout cell selection for aggregate rows that no longer exist after changing the grouping of the grid.