Comment 18 for bug 984197

https://code.launchpad.net/~hono/widelands/984197 has been created with the fix for part 2 of the solution.

Also attached a screenshot of the solution seen in-game.

Tested:
   * Buildings that have Stop & Enhance buttons - there is a separator before the Destroy button
   * Buildings that have Stop button only - there is a separator before the Destroy button
   * Buildings that have neither Stop or Enhance buttons - there is no separator before the Destroy button.

Please review / comment - I'll work on part 1 of the solution now (Ctrl-click to bypass confirmation dialog)