LCG_97a Update, master branch (2020.07.16.)

This MR updates all projects (beside AnalysisBase, but that's another story...) to LCG_97a.

Note that at this instance I didn't set up the projects to use LCG_97a_ATLAS_1, since when I was testing the build yesterday, LCG_97apython3_ATLAS_1 was not available yet. It is now though, so we need to decide in the MR whether I should change to that instead. Still, I wanted to let the CI run during the night for this LCG release at least...

Also note that I had to make a tiny change in TrigPSC, as changes in the externals revealed that one source files in that package did not include all the system headers that it needs.

(As usual, my editor got rid of a number of unnecessary spaces in the files that I edited...)