DEM does not work with "DUMMY_BOUNDARY" (NEXT branch)

[saltynexus]

When I try to apply a DEM to the WaveTank.cu test case, the bottom boundary of the DEM fails and all particles fall through the domain.

In the mean time I'm using "LJ_BOUNDARY" to overcome the issue, but clearly this boundary was abandoned in the "WaveTank.cu" test case for a reason. I don't know what "DUMMY_BOUNDARY" is, or how it helped to improve the WaveTank.cu test case, but it should be applicable to the DEM geometry. I can not take advantage of the improvements presented by "DUMMY_BOUNDARY" until this is fixed.