Rewrite of the BP narrative

All-

In working through ACTION 162
<https://www.w3.org/2015/spatial/track/actions/162> I've taken a good look
at the narrative we plan to use for the Best Practice document. We needed
to include tangible examples the we can elaborate on ...

I offer a second version of the narrative [1] that tries to do this.

You'll find 9 discrete parts, each of which can be elaborated with detailed
examples.

This doesn't represent consensus between the editors as we've not had the
opportunity for wider discussion. However, I wanted to share this with the
wider group prior to the plenary call tomorrow.

Comments welcome - even if it's "back to the drawing board please".

Regards, Jeremy

[1]: https://www.w3.org/2015/spatial/wiki/BP_Narrative_2