Add in the paraview package to hashstack.
ParaView needs the compiler to be explicitly set to MPI.

Normally ParaView doesn't need the compiler overridden, but when we build with
an external netcdf that was linked with MPI, ParaView fails to properly
link all netcdf libraries with MPI, so we modify the compilers to fix
this issue.
Enable paraview package to install development files.

This will allow us to build things against an installed version of paraview.
Patch paraview to support have proper external pv module support.
Explicitly disable objc garbage collection flags, it is not needed now.

This globally fixes the problem that XCode 5+ compilers don't support
obj gc anymore. The flag was pointless since VTK hasn't used the objc
gc for roughly a year now.
Remove unneded file now that we have a patch to use for this issue.
Patch paraview to properly install auto generated headers it needs.

Some of the auto generated ui header paraview creates are referenced from
headers themselves so we need to install them.
Add the mesa library
Paraview: add Mesa to dependencies

It is automatically picked up.
Paraview: make non-relocatable
Make Mesa optional

To enable it, build Paraview with:

  paraview:
    build_with: |
      mesa
Use ${MPICC}/${MPICXX} for MPI compilers

And use e.g.

  mpi:
    use: mpich

or

  mpi:
    use: host-mpi

to set those variables for your system.
Merge pull request #383 from hashdist/paraview

Add paraview