First revision of utils/simplify that actually works.

The lambda term has been removed because I don't really need it. I haven't
factored out vectors a and c because apparently I am too stupid to do this.
This is a more symmetric expression w.r.t. a, b.

I remember testing this exact expression some commits earlier and it produced
whacky error vectors. Don't know for the life of me what went wrong back then.
_views/geojson now lists GeoJSONs of ascending accuracy.

The principle is simple and easy to understand:
1) Simplify with an infinite error; this will result in a useless two-point
   geometry. Note the accuracy of this geometry and discard it.
2) Simplify again, but use half of the accuracy of the last geometry as error.
   Again, note the accuracy.
3) Then it is step 2 until error reaches zero.
Also I reduced the stupidity of my view output and stored bbox and crs in
GeoJSON[0] only. _list/bbox-filter was modified to retrieve these objects from
there. It still doesn't look that cool.