Support PETSc

This release adds support for the PETSc solvers for solving in parallel.

Pulls

• Add support for PETSc solvers (#701)
• Assorted fixes while supporting PETSc (#700)
  • Fix print statements for Py3k
  • Resolve Gmsh issues
  • Dump only on processor 0
  • Only write timetests on processor 0
  • Fix conda-forge link
  • Upload PDF
  • Document print option of FIPY_DISPLAY_MATRIX
  • Use legacy numpy formatting when testing individual modules
  • Switch to matplotlib's built-in symlog scaling
  • Clean up tests
• Assorted fixes for benchmark 8 (#699)
  • Stipulate --force option for conda remove fipy
  • Update Miniconda installation url
  • Replace _CellVolumeAverageVariable class with Variable expression
  • Fix output for bad call stack
• Make CircleCI build docs on Py3k (#698)
• Fix link to Nick Croft's thesis (#681)
• Fix NIST header footer (#680)
• Use Nixpkgs version of FiPy expression (#661)
• Update the Nix recipe (#658)

Fixes

• #692: Can't copy example scripts with the command line
• #669: input() deadlock on parallel runs
• #643: Automate release process