Grids: better fix for issue #0023735.
Set FRowAutoInserted to false in TCustomGrid.EditorShowChar (unless the editor popped up due
to the user pressing backspace).


git-svn-id: http://svn.freepascal.org/svn/lazarus/trunk@39955 4005530d-fff6-0310-9dd1-cebe43e6787f