Fix Surface container problem in LocalEstimatorFrom... and associated tests and examples.
Merge branch 'FixLocalSurfelEstimator' of github.com:JacquesOlivierLachaud/DGtal into VCM

Need to merge while waiting for merge in master.
Fix bug in ElementaryConvolutionNormalVectorEstimator.h
Add hat functions.
Fix in ImplicitDigitalSurface.
Remove container vector<Point> from VCM.
First version of VCM on digital surfaces.