Cherry-pick "Merge branch 'DoxygenRevival-master-20180917' into 'master'" into 1.0

Doxygen Target Revival, master branch (2018.09.19.)

See merge request !342 (merged)

(cherry picked from commit b9a699ca)

• ef254dee Revived the "doc" target for ATLAS projects.
• 82cd70c6 Protected the Doxygen code against directory names with spaces in them.