refactor(handlers): Add types for outputting data

- add trait for formatting outputs
- add types for presenting data to the output
- refactor offline mod to use types

Author: tvpeter

src/handlers/mod.rs

@@ -4,6 +4,7 @@ pub mod key;
 pub mod offline;
 pub mod online;
 pub mod repl;
+pub mod types;
 pub mod wallets;
 
 #[cfg(feature = "repl")]