Bumping to Houdini Version: 13.0.402
Houdini Engine Version: 1.7 (API: 13)
In OutputGeomtryPart constructor, call update()

This avoids duplicate code for updating the HAPI_PartInfo.
Avoid creating the mesh node if the part doesn't contain a mesh.

The mesh node is also grouped under its own transform. This is more
consistent with other output types.
Create the grid data with MFnFloatArrayData directly

This avoids an extra copy of the grid data.
In OutputGeometryPart::createVolume, use std::vector to store the tile data
In OutputGeometryPart, move volume code into OutputGeometryPart::createVolume
In OutputGeometryPart::createVolume, reuse MFnFloatArrayData if it already exists