Compare indicator functionality

[santilland]

This branch brings the capability to compare any two indicators. The initial proof of concepts looks quite good. It is possible to enable/disable it by adding enableComparison in the properties for the EodashMap and EodashItemFilter widgets (defaults to false).

There are issues with keeping sync between maps when switching projection, it also seems that in general widgets might load before required things are finished loading and the interaction breaks. I think this is not related to the compare function in itself.

I would propose to merge this sooner rather then later, so that potential new implementation can be tested / developed with this functionality in mind.

In principle i would think following is missing (but not blocking)

• [ ] Integrate second layer control for the comparison map (this would make especial sense once the item / time selection is also integrated into the layer control
• [ ] think about how to handle export map concept when comparison is being used (i am ok with only the main map being exported, but it somehow needs to be communicated to the user)
• [ ] in general i would further test integrating projection changes here to see how it affects both maps

[santilland]

So, with the comparison disabled in configuration i would propose to merge this into our main branch, so that it does not diverge with other developments. It maintains the original functionality and will allow us to better explore the integration with map projections as it will affect the main and comparison map.

[santilland]

Great, thanks! I will delete the branch