Remove current GUI from opSimulation for v1.0

Goal:

• v1.0 should contain new REACT version of GUI (own repo: opGUI)

Approach:

• existing GUI and recent fixes will be tagged with v0.11
• open issues in opGUI need to be reviewed: include minor fixes in v0.11?
• v1.0 development is independent of remaining fixes in existing GUI

The removal of the current Qt GUI concerns: dependencies, build instruction, tutorial, user documentation (PCM use case with GUI), openPASS Jenkins CI