Basic point functors and test
merge from master
fix typo doc
Merge branch 'master' of github.com:DGtal-team/DGtal into FlipDomainAxisFunctor
correct flip doc
surfel estimator functors -> functors::
concepts
edits
Merge pull request #887 from kerautret/FlipDomainAxisFunctor

Flip domain axis functor
resolve conflict
Merge pull request #12 from kerautret/testimatorFunctors

for conflict
Merge pull request #911 from dcoeurjo/estimatorFunctors

surfel estimator functors -> functors::
Merge branch 'master' of github.com:DGtal-team/DGtal into FixGraphNamespaces
Update namespace concepts for surface estimators. Fix docs accordingly.