Make straighten/orthogonalize act like a single operation

- Display only one or the other in the radial menu
- Rename "Orthogonalize" to "Square"
- Use "S" as shortcut for both

Refs #1839
Added the ability to load points from gpx files and display on the map
Clean up
Update togeojson.js to 0.3.0
Don't auto-save intro tutorial edits

Fixes #1745
Fixes #1795
Update imagery
Improve Circularize Action