Add MenuDisableCol

MenuDisableCol is a column type that should be able to disable/enable
other cells in the same row based on the selection the user makes.
Add example MenuDisableCol to TestMenu test device

Added a MenuDisableCol to TestMenu test device.  Presets have numeric
values for the strings, and disables the indicated columns.
Add Default Data.vi to TestDevices/TestMenu

To make the MenuCol (& children) initialize to the top-most menu item, add
Default Data.vi to the class.  Also shows use of the ``To More Specific
Class'' sub-VI to allow access to calls unique to a child class.
Merge branch 'Add-Menu-Column'