Improvements to maps:
* Improved colors for area maps (but still need to get rid of white end)
* Save and restore maps including legend, center, and zoom
* Use L.esri to get backgrounds from ArcGIS
* Improved the way changes in map layer are handled by MapView
* Attribute menu for map legends now shows and works
Merge branch 'master' of https://github.com/concord-consortium/codap
Build 0258
The colors in a map no longer go to white at the minimum. We have introduced a 0.1 offset by setting a new property in AttributePlacementDescription that is used in the computation of minMax.
Undoing inadvertent commit of commented out iframe-phone
* Fixed calculation of categorical colors broken by previous commit
* For continuous legend, justified the min and max numbers so they stay within view
* Fixed point data tips to show the first time (by getting rid of dependence on binding)
Merge branch 'master' of https://github.com/concord-consortium/codap
Server logging can throw an exception if Debug._currentMessage is empty. Catch.
Catch exceptions that may occur when requesting data interactive state during save or export operation.

We will not save or export the data interactive state under those
circumstances,
but we will export codap state.

[#Fixes 75364516]