Move declarations in DoFHandler from protected to private.

DoFHandler still had some of its member variables and functions in a protected
section from back when we still had MGDoFHandler derive from it in a meaningful
way. This is now no longer necessary, so remove the protected section and instead
sort things in some sort of natural way into the private section.
Merge pull request #161 from bangerth/private-protected-cleanup

Move declarations in DoFHandler from protected to private.
DoFHandler still had some of its member variables and functions in a protected
section from back when we still had MGDoFHandler derive from it in a meaningful
way. This is now no longer necessary, so remove the protected section and instead
sort things in some sort of natural way into the private section.
Remove unnecessary #include.
Merge pull request #162 from bangerth/remove-unnecessary-include

Remove unnecessary include
Test lac/SchurMatrix
Test lac/SchurMatrix; Indented
Merge pull request #165 from dakshinai/test_schur_matrix

Add tests for class SchurMatrix
Added OPENCASCADE support to cmake.
Added occ_utilities.
Fixed config.h.in, added a test.
Fixed compilation issues.
Fixed test.
Fixed point ordering.
Added function closest_point to OpenCASCADE namespace.
Added OCC::NormalProjectionBoundary
Added interpolation curve boundary test.
Updated documentation.
Added Axis Projection.
Added write_IGES routine.
Fixed typo in compilation, and header files.