Vistool workover

[schalkdaniel]

ToDos:

• [x] Add optimization techniques (see e.g. here)
• [x] Use a more package-like structure:
  • [x] Clean overall structure
  • [x] Clean documentation
• [x] Flexibility -> Everything should be combinable with everything
• [x] Control the step size of each iteration
• [x] Add an archive for the optimization path and all relevant information (step size, value of objective, etc.)
• [x] More test functions in the dictionary
• [x] Backend for visualizations. Preference: One package for all figures (plotly? check again)

[schalkdaniel]

Moved to https://github.com/slds-lmu/vistool