Ticket #2953: (edit_move_to_prev_col): fix floating point exception.

Signed-off-by: Andrew Borodin <aborodin@vmail.ru>
(insert_spaces_tab): fix floating point exception.

Signed-off-by: Andrew Borodin <aborodin@vmail.ru>
Merge branch '2953_editor_fpe'

* 2953_editor_fpe:
  (insert_spaces_tab): fix floating point exception.
  Ticket #2953: (edit_move_to_prev_col): fix floating point exception.