Tag OpenStreetMap v0.4.0

* Added route planning capabilities (both shortest and fastest paths) using Graphs.jl.
* Wrote documentation.
* Added small gallery of plot examples to GitHub readme.

The capability in this package now exceeds that of the comparable Matlab toolbox (and it runs A LOT faster than it). I have implemented everything I need for my work, and am now out of ideas for additional functionality, so this package probably won't see significant further updates without requests from users. I will continue to make some tweaks to smooth a few things out yet.