Simulates navigator.geolocation position changes for testing mobile web apps
on non-mobile devices. Sadly, while this code works as advertised, Firefox
doesn't poll for position updates unless the list of wifi networks your
computer can see changes.

The idea behind this app was to use it as a mock geolocation provider (instead
of Firefox's default one, which looks up your location by sending the list of
wifi networks your computer can see to Google). The code accepts queries like

?path=<polyline>&start=<timestamp>&speed=<speed>

and, on each load, calculates the position of an imaginary traveler which began
its journey at time <timestamp> and is traveling at constant speed <speed>
along the path defined by <polyline>.

(What's a polyline? It's a series of latitude/longitude points encoded using an
algorithm Google devised. You can create your own polyline at:

http://code.google.com/apis/maps/documentation/utilities/polylineutility.html )

So, a browser's geolocation service repeatedly checking the result from that
query would get new locations progressively farther along the path, simulating
movement within the defined parameters. Awesome and useful, right?

Unfortunately, Firefox only triggers the geolocation watchPosition() callback
when it notices that the list of wifi networks your computer can see has
changed, so while geowifisim correctly delivers a location near the start of
the defined path the first time you do a geolocation lookup, watchPosition()
never fires again, and movement is not simulated.

A workaround would be writing your code to do periodic getCurrentPosition()
calls when you're debugging on a desktop, and only test the actual
watchPosition() when you're testing on a real mobile device.

REQUIREMENTS:
Flask: http://flask.pocoo.org/
$ pip install Flask

USAGE:
$ python geowifisim.py
Runs a simple webserver hosting the app on http://127.0.0.1:5000