Merge MDA branch

MDA interactive browser (https://atlasdaq.cern.ch/info/mda/app/mda.html) was implemented on a branch of webis and I was running it from that branch for 5 years already. I think it's time to finally merge it into master. I have copied changed from old branch (mda-browser-20150320) to this new branch and shuffled files around so that all MDA stuff now lives in mda/ folder. One small change was needed to lib/ext-atlas.js to allow customization of one panel in MDA browser.

Fixes ADHI-4752.