Merge branch 'master' into willic3/fix-plasticity

* master:
  More updates for partitioner setting to PETSc.
  Use PETSc partitioner setting.
  Fixed partitioner settings.
  Update Distributor for moving partitioner to PETSc setting.
  Updated Distributor Python object for removal of partitioner parameter.
  Fixes to comments.
  Distribution: Fixed interface to DMPlexDistribute()
Some changes to plasticity section plus changed version of LyX to older
version.
Added test for plasticity + initial stress (3d).
Modified Drucker-Prager for the case where there is no plastic yield and
tensile yield is not allowed.
Added missing makefiles.
Added 2D version of plasticity test and moved existing plasticity
tests down a level. They probably need updating.
Updated userguide to describe feasible stress state.
Cleaned up cfg files and dir structure for 2-D plasticity test.
Cleanup of Makefiles for creating source distribution.
Cleanup of 3-D plasticity test.
Fixed makefiles for 3-D plasticity test.
Merge branch 'willic3/fix-plasticity'

* willic3/fix-plasticity:
  Fixed makefiles for 3-D plasticity test.
  Cleanup of 3-D plasticity test.
  Cleanup of Makefiles for creating source distribution.
  Cleaned up cfg files and dir structure for 2-D plasticity test.
  Updated userguide to describe feasible stress state.
  Added 2D version of plasticity test and moved existing plasticity tests down a level. They probably need updating.
  Added missing makefiles.
  Modified Drucker-Prager for the case where there is no plastic yield and tensile yield is not allowed.
  Added test for plasticity + initial stress (3d).
  Some changes to plasticity section plus changed version of LyX to older version.