added 3d voxel geometry plotting capability
Merge branch 'master' into raster3d
Added python utility to parse 3d voxel plot dump into silo file
Updated plotting output summaries
Added warnings for ignored plot options for voxel plot
Changed '3d raster' name for new plotting capability to 'voxel'
Simplified header write statement
Updated user's guide with info on voxel plots
Removed unnecessary xyz coords in voxel binary dump
Fixed lower_left point and output width print
Removed debug print statement
Merge pull request #169 from mit-crpg/raster3d

New plot type: 3D voxels