Add a section discussing consequences.

This pertains in particular to the question of getting discontinuous
geometries when using manifolds and a discussion of what that means,
if it is important, and if it could be fixed.
Merge pull request #140 from bangerth/add-note-to-step-53

Discuss geometric issues.
add documentation on the effect of ConstraintMatrix::distribute_local_to_global() on eigenvalues
Improve the documentation for step-52.
Further polishing of documentation after comments
Merge pull request #142 from Rombur/step_52

Improve the documentation for step-52.
Added TriaAccessor::point function, which returns points on the manifold given their unit coordinates.

Simplified Manifolds::get_default_quadrature.
Fixed WB comments, and a leftover which got messed up when squashing.
Addressed last comments by WB.
Merge pull request #144 from luca-heltai/pr_tria_accessor_manifold_aware

Made TriaAccessor aware of Manifold.

This is the initial work to make TriaAccessor more aware of Manifold.

This allows (and future PR will implement this) to switch internal calls to get_manifold to syntax like

cell->center(true);
line->center(true):
line->point(p);
instead of the fairly redundant versions

cell->get_manifold().get_new_point_on_cell(cell);
line->get_manifold().get_new_point_on_line(line);

vector<Point<2> > ps(2); ps[0] = line->vertex(0); ps[1] = line->vertex(1);
vector<double> ws(2, .5);
Quadrature<2> quadrature(ws, ps);
line->get_manifold().get_new_point(quadrature);
Refactored tria to use TriaAccessor::center.
Add a version of MPI_InitFinalize that adaptively determines the number of threads.
Fixed typo.
Merge pull request #145 from luca-heltai/pr_refactor_tria

Refactored Triangulation to use TriaAccessor::center.
Bugfix: Only include ./bundled/setup_bundled.cmake

Remove a stray globbing expression that is not necessary any more and that
indeed leads to a subtle issue when configuring in-source with
  $ cmake .

In this case ./bundled/cmake_install.cmake was accidentally picked up
leading to a file permission error if CMAKE_INSTALL_PREFIX was left at the
default /usr/local
use the fe index also in the case where triangulation was prepared for pure refinement

and add test that would fail without the patch and works fine now
Merge pull request #148 from tamiko/fix_bundled_configuration

Bugfix: Only include ./bundled/setup_bundled.cmake
Merge pull request #141 from eisbaerli/solution_transfer

Solution transfer
Merge pull request #143 from guidokanschat/distribute_local_to_global_documentation

Documentation update highlighting the difference between the two ConstraintMatrix::distribute_local_to_global() functions for matrices and their effect on the spectrum of a matrix
Add some documentation.