Split some files and add more documentation

src/interface.rs

@@ -2,6 +2,10 @@ use log::{debug, trace};
 
 use super::{device::Obd2BaseDevice, Error, Obd2Device, Result};
 
+/// An OBD-II interface
+///
+/// Wraps an implementor of [Obd2BaseDevice] to allow for higher-level usage of the OBD-II
+/// interface.
 #[derive(Default)]
 pub struct Obd2<T: Obd2BaseDevice> {
     device: T,