Allow using the old std_cxx1x namespace.

This was supposed to work in a backward compatible way but I broke
it for everyone who didn't explicitly #included the old base/std_cxx1x/*h
headers but got stuff through indirect #includes.
Fix up coding style.

Use CamelCase for class names for this internal class.
Merge pull request #238 from bangerth/fixup-style

Fix up coding style.
Merge pull request #234 from bangerth/fix-std_cxx1x-vs-std_cxx11-compatibility

Allow using the old std_cxx1x namespace.
Added get_lap_time() to Timer; returning the time taken between the last start()/stop() cycle.
Merge pull request #240 from alrashedf/master

Added get_lap_time() to Timer
Added description of occ.
add documentation to deprecated functions in PETSc::MPI::Vector
Merge pull request #242 from tjhei/petsc_documentation_fixes

add documentation to deprecated functions in PETSc::MPI::Vector
Merge pull request #241 from luca-heltai/occ-entry

Added description of occ.
Add OpenCASCADE installation instructions.
Merge pull request #243 from bangerth/add-occ-blurb

Add OpenCASCADE installation instructions.
Allow default paths for opencascade detection

OPENCASCADE_DIR is just a hint and might be invalid.

(In FindTRILINOS.cmake the full path is known due to the inclusion of the
Trilinos project configuration. Thus, those options ensure that no wrong
library is accidentally picked up.)
Merge pull request #244 from tamiko/fix_opencascade_detection

Allow default paths for opencascade detection
Fix GridTools::distort_random for distributed meshes
Minor documentation update. Reorder two functions.
Move communicate_locally_moved_vertices to parallel::distributed::Triangulation.
Add a test for communicate_locally_moved_vertices and verify that its output is correct.
Introduce GridTools::get_locally_owned_vertices().

Also use it in an existing test and in an assertion.
Revert to the old code for the sequential case to maintain backward compatibility. Adjust testcases.

Minor reworks.