Fix column menu with two grids: move from self to scope

Moved most of column-menu methods and variables onto $scope
so that context didn't get misaligned, and therefore two grids
is possible.  Added tutorial page showing two grids.

This is dependent on the previous pull request to add
the hide column menu only because both are in the same file
and I wanted to reduce any merge conflicts.

Should fix #1509, #1506, #1485 (all tested with my specific use cases).