Added Spline interpolation with derivatives.
Changed uint to unsigned int.
Using LU decomposition with complete pivoting for better accuracy.
Fixed type mixing issues.
Removed tabs and fixed indentation.
Merged.
IndexArray is now a typename.

Changed interpolate with derivatives test to use VERIFY_IS_APPROX.
Fix bug 836: extend SparseQR to support more columns than rows.
Removed the deprecated EIGEN2_SUPPORT, as previously announced. A compilation error is raised, if this compile-switch is defined. The documentation references to the corresponding pages from Eigen3.2 now. Also, the Eigen2 testsuite has been removed.
Fix regeression in bicgstab: the threshold used to detect the need for a restart was much too large.
Do not attempt to include <intrin.h> on Windows CE
LDLT is not rank-revealing, so we should not attempt to use the biggest diagonal elements as thresholds.
Fix unused typedef warning
Fix regression introduced by 17d2d0880:
Matrix<Scalar,1,1>(int) did not compile if Scalar is not constructible from int. Now this falls back to the (Index size) constructor.
Fix dox for namespaces
Document internal namespace
Move Doxygen-only stuff to *.dox
Percent "Eigen" in dox to prevent linking if not referring to the Eigen namespace
Mark internal namespace as \internal
Fix dox at internal::tridiagonal_qr_step