varregion: add --displacement parameter to 'load oar'.
Adds displacment to all objects and terrain loaded from the oar.
As an example, if you have a 512x512 region and an old 256x256 oar, doing
  load oar --displacement "<128,128,0>" oarFile.oar
will load the object (and terrain) into the middle of the 512x512 region.
If displacement is not specified, 'load oar' works like it always has.
If you have a 5