Implement native client core lifecycle (#51)

crates/libremetaverse/src/lib.rs

@@ -5,6 +5,7 @@ extern crate self as libremetaverse;
 #[rustfmt::skip] // Deterministic machine output is formatted by the pinned generator.
 mod attention_catalog;
 mod bit_pack;
+mod client_core;
 #[rustfmt::skip] // Deterministic machine output is formatted by the pinned generator.
 mod foliage_catalog;
 mod generated;
@@ -195,6 +196,9 @@ impl imaging::Baker {
     }
 }
 
+pub use client_core::{
+    ClientCoreError, ClientLifecycleState, ClientService, GridClientBuilder, ShutdownPhase,
+};
 pub use generated::*;
 pub use libremetaverse_imaging as imaging_abstractions;
 pub use libremetaverse_structured_data as structured_data;