DOC: improved checking of dependences and, if required, modifies bash_profile.
DOC: improved checking of dependences and, if required, modifies bash_profile.

Former-commit-id: 10f3b4b8682fc6c37e222387260927bfacc261f6
Former-commit-id: ca898ec7511afd46f5e5d21f0231489dbb6930e6
3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox