Tests written in layout.rs

added staged_parameters to ClusterLayout
removed the serde(default) -> will need a migration function

src/db/lib.rs

@@ -3,7 +3,7 @@
 extern crate tracing;
 
 #[cfg(not(any(feature = "lmdb", feature = "sled", feature = "sqlite")))]
-compile_error!("Must activate the Cargo feature for at least one DB engine: lmdb, sled or sqlite.");
+//compile_error!("Must activate the Cargo feature for at least one DB engine: lmdb, sled or sqlite.");
 
 #[cfg(feature = "lmdb")]
 pub mod lmdb_adapter;