merge for v8.2.1

[raphaelquast]

A first bugfix release for v8.2

🔨 fixes

• ❗fix identification of default shape based on dataset size
• ❗fix issues with unmanaged artists on inset-maps
• explicitly check if norm is provided as string before setting data limits
• provide more descriptive (info) error message if data cannot be plotted
• avoid using classification bins as labels if a large number of bins is used (>30)
• make sure to resample colormaps in case more bins than colors are used
• avoid shape radius estimation if no data is set
• avoid unnecessary draw-triggers for datasets if the "all" layer is visible
• remove warning for widgets if backends other than "ipympl" are used