Add the beginning of item entities

Add a new Item raw type and entity type, with preliminary, basic support
for food. There's a really frustrating toml-rs bug that prevents writing
these nicely as toml right now, so I also added support for mixing JSON
and TOML in a single config dir

Cargo.toml

@@ -14,6 +14,7 @@ itertools = "*"
 lazy_static = "*"
 log = "*"
 log4rs = "*"
+matches = "0.1.8"
 maplit = "^1.0.1"
 nom = "^5.0.0"
 prettytable-rs = "^0.8"
@@ -23,6 +24,7 @@ rand = {version = "^0.7.0", features = ["small_rng"]}
 serde = "^1.0.8"
 serde_derive = "^1.0.8"
 serde_json = "*"
+serde_yaml = "0.8"
 termion = "*"
 toml = "^0.5.1"