functionality for finding nodes within range

[yeesian]

To (eventually) provide drivetime isochrones.

Here's an example notebook to demonstrate how nodesWithinRange, nodesWithinDrivingDistance, and nodesWithinDrivingTime can be used.

Just in case the link to the example notebook is down, here's a pdf Related to #43.

[coveralls]

Coverage increased (+0.11%) when pulling a6558c0bf5770b36adc38df90b705612f464669d on yeesian:master into 84eac325777194aa8e7abdddc524b968d8b6ef4e on tedsteiner:master.

[tedsteiner]

This is really really cool! And a really relevant application, too. Thank you so much for adding this, it will be useful for some things that I'm working on, and I'm sure many others, too.

Thank you for adding tests for these features, too. One question about that - is the order in which nodes appear in node_indices in the routing test deterministic? Is there a chance that changes to Julia might result in the test being out of order? And is the order important? If not, would be better to write the test lines as @test 575444707 in node_indices rather than @test node_indices[1] == 575444707 Doing so then requires a search for the correct index before performing the distance test, but I don't really mind making the Travis build machines work a little harder. :)

Also, those plots in your notebook are pretty cool. If you're interested, I would be supportive of adding a function providing a nice and convenient means to display these results. I'd also be happy to add a picture to the examples album, if you'd like to show off your work. Something like an image of all locations within 5, 10, and 15 minute range of hospitals or fire departments in a city would really showcase these capabilities you've added.

I'm going to add an issue to document these new features to make them easier to use. If you're willing to take that on, it would be really awesome. I think your example notebook already pretty much covers how to use them, so hopefully it wouldn't be too much extra work.

Thanks again!