change typedef style, add optional logging

src/lib.rs

@@ -43,3 +43,11 @@ pub struct UdpSocket;
 
 /// This is a type only used by cbindgen to have a type for pointers.
 pub struct DisplayBitVec;
+
+#[cfg(feature = "env_logger")]
+pub mod feature_env_logger {
+    #[no_mangle]
+    pub unsafe extern "C" fn init_env_logger() {
+        env_logger::init();
+    }
+}