MT textbox

Do not show a dialog when the user only shows or hides comment on a shape
To avoid confusion between a text shape and a comment on a shape, I have renamed the text on a shape to 
comment.
See https://trac.openmicroscopy.org.uk/ome/ticket/9742


To test:
 * Open an image
 * Open the measurement tool (MT). Make the text in toolbar is "Show Comment"
 * Draw few shapes, add text to some of them. Save
 * Select a shape, Go to inspector Tab, Make sure the name of the column is "Comment"
 * Close MT and Viewer
 * Open Viewer/MT
 * Text should be displayed on shape.
 * Un-select "Show Comment". The text on shape should no longer be displayed. Do not perform other actions.
 * Close MT. Close Viewer. A Dialog indicating if you want to save ROI should NOT pop up.
 * Open Viewer, open MT. Move a shape
 * Close MT. Close Viewer. A Dialog indicating if you want to save ROI should pop up.


This is TAB, so PR should be rebased to 5.0.0