Merge remote branch 'upstream/master' into ExternalsUpdateForQt-master-20170615

Conflicts:
	Projects/AthSimulation/externals.txt
	Projects/Athena/externals.txt

Resolved two minor conflicts in Athena/externals.txt and AthSimulation/externals.txt.
At the same time updated the externals.txt files a bit to try to prevent similar
conflicts to appear in the future. (By moving the "changable" lines in the files
a bit further apart.)