Cleanup of some names of Field methods.

Improve names of Field methods for creating subfields. Removed
newSection(void). Added some helper functions for setting DOF in
sections when newSection(args) won't work.
Turn off some debugging output.
Update method name.
Worked on updating fault unit tests for interpolated meshes.

Updated creation of fields to account for Lagrange multipliers on edges.
Improved tests to make them more robust.
Merge branch 'knepley/upgrade-petsc-interface' of github.com:geodynamics/pylith into knepley/upgrade-petsc-interface

* 'knepley/upgrade-petsc-interface' of github.com:geodynamics/pylith:
  MeshIO: Updated VTK Mesh tests - Note that data on the hybrid edges is now not tested
  MeshIO: Change check for groups to only use original points