Add nom [1] dependency

We enable the "nightly" feature to get better error messages. Nightly
is needed to build this project anyway until `TryFrom` lands [RFC],
[tracking issue].

[1]: https://github.com/Geal/nom
[RFC]: https://github.com/tbu-/rust-rfcs/blob/a4a22d7c5dd71724bb2cd0fe2db5026338d0b270/text/1542-try-from.md
[tracking issue]: rust-lang/rust#33417

Author: daniel-ferguson

Cargo.lock

@@ -7,3 +7,7 @@ authors = ["Daniel Ferguson <[email protected]>"]
 env_logger = "0.3"
 log = "0.3.8"
 termion = "1.4.0"
+
+[dependencies.nom]
+version = "3.2"
+features = ["nightly"]