Use latest `sporto/erl`

This uses the latest version of the sporto/erl dependency (in fact, it can use version 11, 12 or 13).

It is a major version bump because of changes in RouteUrl.Builder. The difference is the from sporto/erl 11 onwards, the query portion of the URL is modelled as a List (String, String) rather than a Dict String String. This is clearly better, since a URL query can have duplicate "keys". But it does mean a breaking change in the API.

Update elm-update-extra dependency

This is a patch release to enlarge the version bounds of the ccapndave/elm-update-extra dependency.

Update for Elm 0.18

Version 3.0.0 updates elm-route-url for use with Elm 0.18.

Fix problem with root URL

Version 2.0.1 fixes a problem which occurred when routing the root URL -- that is, when routing "/".

Update for Elm 0.17

Updates elm-route-hash for Elm 0.17, and changes its name to elm-route-url, since you are no longer limited to just working with the hash.

Update for Elm 0.16

1.0.5

Update for Elm 0.16.

Document how to work with an unmodified start-app

I originally thought that elm-route-hash required some minor changes to start-app. However, it turns out that there is a way to avoid that -- the README now describes how.

Avoid infinite loops

Fises #3, which could cause an infinite loop when returning multiple actions in response to a URL change.

Better documentation

I had been experimenting with a table of contents in the documentation, but it turned out to be easier than I thought!

Fix dependencies

Needed to loosen the version bounds for the evancz/elm-http dependency.