Advent of Code 2015 in rust

This library uses cargo-aoc as runtime.

1. Install cargo-aoc with

   cargo install cargo-aoc

2. Log in to the Advent of Code site.
3. Open developer tools, and navigate to Application -> Storage -> Cookies -> https://adventofcode.com
4. Copy the value of the "session" cookie.
5. Save the cookie to cargo-aoc with

   cargo aoc credentials {token}

6. Run with

   cargo aoc run