Selecting two full lines including line ends makes a selection from
line 1 to line 3 (ch: 0). This command used to sort three lines (1 to
3) which is not what I expect. This change makes it sort only two
lines if there are no selected characters on the last line.

It also fixes a fatal error if there are more than one selection on
the same line (the code used 'range' instead of 'ranges').

It also selects the trailing newline after sorting the lines so that
the whole lines are selected.