Reach geometry editor [WIP]

This allows users to edit geometries for rivers (or create them for new rivers).

TODO:

[x] allow it to attempt to work when the whole geometry is not in the viewport -- can use existing geom to supplement...find where existing geom intersects viewport, use that as the endpoint for calculateGeom, then slice the existing geom at that intersection point and add the newly calculated section
[x] optimize if possible?
[x] hook up "save"
[x] see if I can make a Mapbox studio service that displays NHD at lesser zooms
[x] make it possible for users to zoom out further, just deactivate interaction
[x] consider allowing users to modify the line directly (with no snapping or calculation) after the fact?
[x] allow creation of geoms when it doesn't already exist (i.e. reach creation)
[x] make the geom in edit mode bigger
[x] add visual distinction between put-in and takeout and some warnings about weird behavior if you flip them

AmericanWhitewater / wh2o-vue