Restructure proto

The existing code has been moved out and is being copied back piece / by
piece while restructuring the code to (hopefully) be more manageable.

src/frame/settings.rs

@@ -66,21 +66,10 @@ impl Settings {
         }
     }
 
-    pub fn new(values: SettingSet) -> Settings {
-        Settings {
-            flags: SettingsFlags::empty(),
-            values: values,
-        }
-    }
-
     pub fn is_ack(&self) -> bool {
         self.flags.is_ack()
     }
 
-    pub fn into_set(self) -> SettingSet {
-        self.values
-    }
-
     pub fn load(head: Head, payload: &[u8]) -> Result<Settings, Error> {
         use self::Setting::*;