Use the Ptr typedef from the class in CorrespondenceEstimation...::clone. (+1 squashed commit)
Squashed commits:
[501eb1b] Add typename in CorrespondenceEstimation::clone.
Merge pull request #655 from salino/RegistrationCompilationErrors

Fix for compilation errors in Registration module.
Various doxygen fixes
Merge pull request #654 from VictorLamoine/doxygen_fixes

Various doxygen fixes