Add otb::DEMHandler ::ClearDEMDirectory() and ::ClearGeoidFile() interface.
Mantis Issue 1071, reported by salbert, assigned to gpasero, created: 2015-09-15
Monteverdi2 needs to clear DEM-directory and/or Geoid-file when the user disables and/or clears those settings.
1443627323 - gpaseroBugfix merged here: https://git.orfeo-toolbox.org/otb.git/commit/27efb1cc71bdec877513417a07c70a2a1714f822