First attempt at hierarchicaly visibility images#493

frank-at-adacore wants to merge 4 commits intomasterAdaCore/training_material:masterfrom

slides/120-create-svg-diagram-to-show-hierarchical-visibility-in-program-structure-moduleAdaCore/training_material:slides/120-create-svg-diagram-to-show-hierarchical-visibility-in-program-structure-moduleCopy head branch name to clipboard