Map interaction performance improvements

[oliverroick]

Proposed changes in this pull request

• Resolves Improve performance of Leaflet.Deflate #932
• Switch to a customized version of Leaflet.Deflate to improve the performance of map interactions. (These changes will be added upstream to Leaflet.Deflate at some point). The customized approach includes the following changes:
  • Ignore point features when evaluation whether to show the original feature or the marker.
  • Group features into bins according to the zoom threshold and evaluate only features that were affected by the last zoom action.
  • When evaluating, features ignore everything that is outside the current map view. When the map is panned, the current map view is re-evaluated and updated accordingly. The reevaluation only includes features that have not be evaluated before.
• Removes Leaflet.MarkerCluster.LayerSupport as it is not needed any longer

I have tested this against a data set with 15,000 polygons of varying size and the Uttaran data set.
Uttaran is almost exclusively points; the performance is increased tremendously. The performance of the polygons dataset is reasonable; for instance, takes roughly 350ms to replace ~4000 polygons when looking at an area approximately the size of Hamburg .

When should this PR be merged

For sprint 11

Risks

None

Follow up actions

None