Fix rectangular selection.
Fix rectangular selection.

selsort computes the wrong normalized coordinates when rectangular
selection is enabled, causing rectangular selection to only work
when going toward either the top left corner, or the bottom right
one.

Signed-off-by: Roberto E. Vargas Caballero <7478dba6682c631c29bb5d8db3571688fdd8aa67@shike2.com>

google/mt,google/mt