bpo-39852: IDLE 'Go to line' deletes selection, updates status (GH-18801)

bpo-39852: IDLE 'Go to line' deletes selection, updates status (GH-18801)

It appears standard that moving the text insert cursor away from a selection clears the
selection.  Clearing prevents accidental deletion of a possibly off-screen bit of text.
The update is for Ln and Col on the status bar.
(cherry picked from commit 2522db11df102be3baf25ce9e816ebe8ffdb7fcc)

Co-authored-by: Terry Jan Reedy <tjreedy@udel.edu>