expose ButtonEvent members

this is done using methods instead of just making the member fields
`pub` so that they can't be changed.
the same will have to be done for all other events to make them usable.

Author: rursprung

src/bluefruit_protocol/button_event.rs

@@ -82,3 +82,12 @@ impl TryFrom<&[u8]> for ButtonEvent {
         }
     }
 }
+
+impl ButtonEvent {
+    pub fn button(&self) -> &Button {
+        &self.button
+    }
+    pub fn state(&self) -> &ButtonState {
+        &self.state
+    }
+}

src/bluefruit_protocol/mod.rs

@@ -113,7 +113,7 @@ pub fn parse<const MAX_RESULTS: usize>(
                 }
             }
             ParserState::ParseCommand => {
-                let data_package = extract_and_parse_command(&input[(pos-1)..]);
+                let data_package = extract_and_parse_command(&input[(pos - 1)..]);
                 result.push(data_package).ok();
                 if result.len() == MAX_RESULTS {
                     return result;