Oxidizer v0.9.0

Added

• Events and services between mods, Rust and Rhai alike. Events: publish, publish_retained (kept as the topic's current value for later subscribers) and subscribe, delivered at the start of the next frame. Services: provide and call_service / call, which return a value. Names start with the owning mod's id, and only that mod publishes on or provides them. Values are JSON: maps in Rhai, serde types in Rust (Event and Service traits). Mods > Oxidizer has an Event bus section. Examples: bus_rust and bus_rhai.
• oxidizer_api 0.6.0 (API version 5): the bus and services. Each Rust mod gets its own API table, which carries its id. Mods built with older versions keep working.