combobox cleanup

  - removed unecessary functions that exist already in the superkind
    (XV.Input)
  - cleaned up @todo Document comments

NOTES:
  - relationwidget extends past the horizontal edge of the workspace
    panel, cutting off the search icon. this is temporary.

FIXME:
  - e.g. SalesOrder isn't properly spacing the workspace panels,
    presumably because there is a custom structure there, or because
    they are different sizes and enyo doesn't know what to do.