* Remove seemingly unneeded const on MetadataKey<T> new
* Change biome temperature/moisture to integer, x100 to remove floating-point so can use within stable 'const fn'
* Remove unstable const_fn feature, now using stable const fn: see https://www.reddit.com/r/rust/comments/9msqfn/const_fn_soon_on_stable_rust/
* Test on Rust beta (awaiting 1.31 release for stable)
* Update readme for beta Rust support
* Replace find() with get()
* Update for renamed as_string->as_str and as_boolean->as_bool
https://github.com/serde-rs/json/releases/tag/v0.8.0
Value::as_string() has been renamed to as_str() and Value::as_boolean() has been renamed to as_bool() to improve consistency
https://github.com/serde-rs/json/issues/126
* No serde_json::Value::I64/U64/F64 anymore, only Number
* Update from lookup() to pointer(), using JSON pointer syntax
https://github.com/iceiix/steven/pull/6#issuecomment-432472123
* Remove unused and removed ObjectBuilder import
* Use into_iter().collect() to convert BTreeMap to serde_json::Map
* Change parse_rules to accept serde_json::Map instead of BTreeMap
* Remove unused serde_json macro_use
* Update Cargo.lock