Hid #modify form and uncovered it if file finished loading.
Implemented GeoJSON type 'LineString'.
Provided GeoJSON type to utils/eachCoords callback.
Removed last Polygon coordinate from _view/geojson output.
Revised construction of 'paths' object required by Maps.Polygon etc.

GeoJSON's coordinates have the same structure as the paths property passed to
Google Maps' polygon/polyline/marker constructor. It makes more sense to just
replace the innermost [lng,lat] with a LatLng(lat,long) object and leave the
rest of the structure as it is.
The for-loops look ugly on purpose because they have to be fast.
Fixed bad function utils/stripLastCoord.
Fixed bad coord substitution in map.html.