OP2/PyOP2 — pull request #104 by kynan (2012-11-03 19:54:04+00:00)
Title: Use Petsc4py as the linear algebra backend

Remove the dependency on the _cpp-matrices_ branch of OP2-Common for the PyOP2 matrix support. Matrices and linear algebra operations for the _sequential_ and _opencl_ backend are implemented using _petsc4py_, which provides python bindings for PETSc. It therefore works with the master branch of OP2-Common.

Note that petsc4py currently does not yet supporting building matrices from a CSR structure provided by the user (which is what we want). This capability is implemented in a [fork of petsc4py](https://bitbucket.org/fr710/petsc4py) and proposed for merging in the main petsc4py development repository.

[Passes on buildbot](http://buildbot-ocean.ese.ic.ac.uk:8080/builders/pyop2-testing/builds/451).