be used as intended to specify an installation directory, which can be located anywhere on the
file system.
Also improved the doxygen target and made the doxy build "quiet".
fixes#154
2 client APIs are changed.
- VertexBuffer::UpdateData() takes start vertex offset
- ComputeController::Refine() takes FarKernelBatchVector
Also, ComputeContext no longer holds farmesh.
Client can free farmesh after OsdComputeContext is created.
(but still need FarKernelBatchVector to apply subdivision kernels)