Add TEfficiency support

Add Open Source license files

Add missing includes for TVirtualX class

Add Pixel DQM plugin.

Fix the issue with pop-up histogram window appearing empty. Add time for ROOT events processing.

Use QAction::triggered() signal instead of the obsolete activated() one

Switch to Qt5.

Hide the drop-down menu before connection to MDA archive as otherwise this operation may block the current X11 session.

Fix the bug which can cause corruption of a TStyle object used for histogram painting.

Add .gitlab-ci.yml file.

Install .pcm files

Install missing xml files

Install generated Ui/*.h files

CMake

Fix the bug which can crash the GUI.

Install PCM files.

Add semicolons after ERS macro.

Remove qPixmapFromMimeSource from UI files as it causes run-time symbol resolution error.

Remove unused dependency.

Put back pointer instead of reference to the callback function.