Fixes 773 and update doc of CountedPtr.
Update test testCountedPtr.
Some fixes on CountedPtrxxx + doc + new test.
Some fixes on CountedConstPtrxxx + doc + new test.
Removing ASSERT to speed up Travis in Debug mode.
Uncommenting slow ASSERT since Travis was corrected.
Merge branch 'master' of github.com:DGtal-team/DGtal into Fix773

Synchronising with master
Update ChangeLog.
Merge pull request #894 from JacquesOlivierLachaud/Fix773

Fix773