Collecting the following (more significant) updates: - Picking up some of the externals' sources from the ATLAS webpage now; - Introduced "purgeBuild" steps for some of the externals; - Updated the way HDF5 is built; - Some environment setup fixes for Qt5; - Updated the converter generator code to be compatible with Gaudi v30r2; - Improvements to the Python byte-compilation code; - Updated AthenaExternals to LCG_93; - Added ACTS as an external to AthenaExternals.