responding to Marianne's feedback

[ericnost]

fixes #123 fixes #128 fixes #129 fixes #132 (I think)

These edits do a few things:

• allow downloading the most important data on each page (except welcome and statewide overview)

• changes some styling on "Find" to ensure that facility markers are visible against the blue-filled polygons whose styling we can't change at the moment. For instance, this yellow is now more opaque and hence visible:

  

• on "Find", loads ALL PWS that have something to do with the map bounds. Any PSA that intersects with the map bounds will also see its PWS equivalent loaded, ensuring that the charts at the bottom of the page are accurate

• on "Violations", likewise loads ALL PWS that have something to do with the map bounds, ensuring all facilities have violations displayed. Counts are added to the PSA popups.

• also on "Violations", deals with facilities that have NO recorded violations. Previously, these were dropped, leading to a misleading and perhaps confusing state where facilities would disappear from the map between "Find" and "Violations".

• on "EJ", gets all block groups that intersect with any PSA that intersects with the map bounds, kind of getting towards Marianne's request to summarize EJ data by PSA

• does the same on "Watersheds"

• the above two changes could get unwieldy but we can always change back or limit the zoom in order to limit the data load

[ericnost]

@Frijol - could you take a look? I think these are our last big changes?

[Frijol]

This is amazing! Looks great!