Make field reference more flexible

Will need to support {"rtype": "restriction"} for turn
restriction field.
Trim tag keys, and prevent duplicate tag keys (#2043)
Update regexp, and remove trim from old key..
Use match rather than split
Merge branch 'bhousel-bhousel-fields'
Add turn restriction presets
Deselect before deleting an entity

This avoids errors produced by attempts to generate turns for
ways that were just deleted.
field.geometry is a string, not an array
Extract iD.geo.RawMercator
Extract iD.svg.Defs from Surface

Need to have a single defs for the entire document but
multiple Surfaces.
Start work on turn restriction editing field
Include pick in lodash build
Render turns of selected way
Show turn restriction editor for any intersection
Show ways in restriction editor as if they were split
adding turn restriction assets
Let preset editor preserve field state

The turn restrictions field wants to have selected state.
Use restriction preset icons
Implement basic restriction toggling
Use turn restriction icons