Optimization UI improvements

[jbussemaker]

• Enable sharing the optimization problem to other people (e.g. for inspection or feedback)
• Allow removing or stopping/killing of optimization problems
• Improve insight in infill points generated by the optimizer
  • Display infilled points in a different color in the plots
  • Highlight hovered points in all points (e.g. I'm hovering over a point in one of the scatter plots --> I want to see the same point highlighted in the other plots)
• Better documentation of optimizer settings