Sync with trunk.
Cherry pick a HDF5 fix from trunk.
Merge from trunk:
    Anders Logg 2013-03-07 Update ChangeLog
    Anders Logg 2013-03-07 Get C++ version of LinearOperator unit test runnin...
    Anders Logg 2013-03-07 Get LinearOperator unit test to run in serial (mis...
    Anders Logg 2013-03-07 [merge] Merge:
    Anders Logg 2013-03-07 Add utility script dolfin-get-demos for easy insta...
    Johan Hake 2013-03-07 MeshFunctions now support iterable protocol, fixing...
    Garth N. Wells 2013-03-06 [merge] Merge some fixes.
    Garth N. Wells 2013-03-06 [merge] Merge HDF5 fix
    Chris Richardson 2013-03-06 Build fix
    Garth N. Wells 2013-03-06 Add an assert in PETScMatrix
    Anders Logg 2013-03-06 Skip LinearOperator unit test for backends that ar...
    Anders Logg 2013-03-06 Improve error message when setting parameter out o...
    Anders Logg 2013-03-06 Fix small typo
    Anders Logg 2013-03-06 [merge] Merge:
    Anders Logg 2013-03-06 Get LinearOperator to work again after rename of f...
    Anders Logg 2013-03-06 [merge] Merge merge of keep_diagonal patch from Ja...
    Anders Logg 2013-03-06 [merge] Merge:
    Jan Blechta 2013-02-19 more informative error message on bug 1033611
    Jan Blechta 2013-02-18 expose keep_diagonal to python
    Anders Logg 2013-03-06 [merge] merge
    Anders Logg 2013-03-06 Small fix
    Anders Logg 2013-03-06 [merge] merge
    Patrick Farrell 2013-02-20 And the rest of the updates.
    Patrick Farrell 2013-02-20 Merge some of the revisions, but not all?? Bzr...
    Anders Logg 2013-03-06 [merge] merge
    Anders Logg 2013-03-06 [merge] merge
    Anders Logg 2013-03-06 [merge] merge
    Anders Logg 2013-03-06 Minor formatting fixes
    Anders Logg 2013-03-06 [merge] Merge improved harmonic smoother by Jan Bl...
    Jan Blechta 2013-03-06 HarmonicSmoothing: changed return type to shared_p...
    Jan Blechta 2013-03-06 fix bug in MeshDisplacement copy ctor
    Jan Blechta 2013-03-06 HarmonicSmoothing returns displacement.
    Jan Blechta 2013-03-05 HarmonicSmoothing remove unncessary code for displ...
    Jan Blechta 2013-03-04 swig typemap std::vector<dolfin::la_index>, expose...
    Jan Blechta 2013-03-04 HarmonicSmoothing: keep only displacement mode
    Jan Blechta 2013-03-04 update swig docstrings
    Jan Blechta 2013-03-04 get rid of compute_vertex_values in HarmonicSmoothing
    Jan Blechta 2013-03-04 introduced new dof_to_vertex_map
    Jan Blechta 2013-03-02 fix bug 1047641 + some improvements to HarmonicSmo...
Backport fix for the linear solver identification problem from trunk.
Backport fix for #1095679 from trunk.
Abuse dynamic typing to fix lp:1130354 and lp:1079772
  -- We now cast a cpp.Function into a dolfin.Function without 
     re-creating the cpp.Function returned from Function.{child,parent,
     leaf_node,roo_node}
Backport fix in swig wrapping of csg polygons.
Backport fixes for setting mesh resolution when generating 2D meshes.
Backport fix for bug #1154991.
Require CGAL 4.1.
Backport bugfix for #1143977 from trunk.
Update to 1.2.x branch in release.conf.
Update version number to 1.2.0 and required UFC 2.2.0.
Update version number to 1.2.0+.
Merge from 1.2.x:
  Johannes Ring 2013-03-24 Update version number to 1.2.0+.
    Johannes Ring 2013-03-24 Update version number to 1.2.0 and required UFC 2.2.0.
    Johannes Ring 2013-03-24 Update to 1.2.x branch in release.conf.
    Johannes Ring 2013-03-21 Backport bugfix for #1143977 from trunk.
    Johannes Ring 2013-03-21 Require CGAL 4.1.
    Benjamin Kehlet 2013-03-16 Backport fix for bug #1154991.
    Benjamin Kehlet 2013-03-15 Backport fixes for setting mesh resolution when g...
    Benjamin Kehlet 2013-03-13 Backport fix in swig wrapping of csg polygons.
    Johan Hake 2013-03-11 Abuse dynamic typing to fix lp:1130354 and lp:1079772
    Johannes Ring 2013-03-11 Backport fix for #1095679 from trunk.
    Johannes Ring 2013-03-11 Backport fix for the linear solver identification p...
    Anders Logg 2013-03-07 [merge] Merge from trunk:
    Garth N. Wells 2013-03-06 Cherry pick a HDF5 fix from trunk.
    Johannes Ring 2013-03-06 [merge] Sync with trunk.