Add FromGraph trait, and add implementation for FrozenGraph

src/lib.rs

@@ -145,7 +145,8 @@ pub mod traits;
 /// Convenience re-exports of graph topology traits for common use.
 pub mod prelude {
     pub use crate::traits::{
-        GraphTopology, GraphTopologyAddition, GraphTopologyDeletion, Incidence, IncidenceCursor,
+        FromGraph, GraphTopology, GraphTopologyAddition, GraphTopologyDeletion, Incidence,
+        IncidenceCursor,
     };
 }