fix cmake warning
Merge pull request #693 from elcerdo/fixCmakeWarning

fix cmake warning
Merge branch 'master' of github.com:DGtal-team/DGtal into testBoard3D
start doc edits with Board3D (issue empty pages on Board3D)
completing doc for Board3D and example fix
removing @code with @snippet
adding image in examples description (from listing) for Board2D
Merge pull request #5 from kerautret/testBoard3D

Test board3 d