[GRASS-git] [OSGeo/grass-addons] 070abd: i.edge: add -n flag for empty input/output (#460)

[Markus Metz]

  Branch: refs/heads/master
  Home:   https://github.com/OSGeo/grass-addons
  Commit: 070abd5fbbc20d9b6afd2ae889618ffe4e6eeb6f
      https://github.com/OSGeo/grass-addons/commit/070abd5fbbc20d9b6afd2ae889618ffe4e6eeb6f
  Author: Markus Metz <33666869+metzm at users.noreply.github.com>
  Date:   2021-03-01 (Mon, 01 Mar 2021)

  Changed paths:
    M grass7/imagery/i.edge/canny.c
    M grass7/imagery/i.edge/main.c

  Log Message:
  -----------
  i.edge: add -n flag for empty input/output (#460)

* add -n flag to create empty output if input is empty
* do not compare signed and unsigned integers