Add Eigen3 package (needed by latest DOLFIN).
Add SWIG bin dir to PATH when build dpendency and set SWIG_LIB environment variable.
Remove Armadillo package (no longer needed by DOLFIN).
Add cmake to build dependencies for CMake packages.
Add mpi to build dependencies for hdf5 package and set CC to MPICC.
Add pkgconfig dir to PKG_CONFIG_PATH for libxml2 package.
Add some extra flags when configuring openmpi package.
Add pkg-config package.
Fix building trilinos with umfpack and add trilinos site-packages dir to PYTHONPATH.
Update vtk package:

- Add python to build dependencies.
- Revert to version 5.10 (had problems with version 6.0).
- Add extra configure flags (not sure how to specify path to python
  library when using host-python).
Add package for pastix.
Add host package for swig.
Add patchelf package.
Update indentation for openblas, parmetis and suitesparse.
Build shared libs for bzip2.
Minor update for cgal package.
Change download url for gmp package since ftp is not supported.
Add variables for python, swig, pkg-config and pastix in debian.yaml."
Fix building petsc with trilinos.
Add petsc4py package.