GridGenerator::flatten_triangulation.

Added GridTools::flatten_triangulation + one test.

Fixed WB comments.

Moved flatten triangulation to GridGenerator.

Fixed TH and WB comments.

Fixed indentation issue.
Merge pull request #95 from luca-heltai/flatten_triangulation

GridGenerator::flatten_triangulation: Gives the ability to copy a flattened version of a Triangulation, with possibly different spacedims.
Rename output of tests that need PETSc, not Trilinos.
Merge pull request #99 from bangerth/fix-test-signature

Rename output of tests that need PETSc, not Trilinos. The tests actually use PETSc, but their output names suggested that they need Trilinos. This was wrong.
Silence a warning from gcc 4.9.1.

The warning pertained to the fact that we define a function in an anonymous
namespace that is only called from a function inside an #ifdef ... #endif
block. The solution is to move the function into #ifdef ... #endif as well.

This addresses this test result: http://cdash.kyomu.43-1.org/viewBuildError.php?type=1&buildid=11683
Fix a warning about undefined behavior.

I get an error of the form
  /u/bangerth/p/deal.II/1/dealii/include/deal.II/meshworker/dof_info.h:69:9: runtime error: load of value 216, which is not a valid value for type 'bool'
when running the testsuite with the ASAN framework. This is caused by the DoFInfo
class having a member variable that is left uninitialized in the constructor.
Fix this.
Merge pull request #100 from bangerth/silence-warning-2

Silence a warning from gcc 4.9.1. The warning pertained to the fact that we define a function in an anonymous
namespace that is only called from a function inside an #ifdef ... #endif
block. The solution is to move the function into #ifdef ... #endif as well.

This addresses this test result: http://cdash.kyomu.43-1.org/viewBuildError.php?type=1&buildid=11683
Merge pull request #101 from bangerth/fix-uninitialized-variable

Fix a warning about undefined behavior.