*: use latest ffmpeg-sys using bindgen

* Update bindings to newest ffmpeg version for new ffmpeg-sys, which is mostly generated by bindgen
* Bring back removed feature flags
* Fix whitespace formating
* Remove prepended enum names to enum variants
* Remove unneeded allows

src/format/context/output.rs

@@ -106,7 +106,7 @@ pub fn dump(ctx: &Output, index: i32, url: Option<&str>) {
 	let url = url.map(|u| CString::new(u).unwrap());
 
 	unsafe {
-		av_dump_format(ctx.as_ptr(), index,
+		av_dump_format(ctx.as_ptr() as *mut _, index,
 			url.map(|u| u.as_ptr()).unwrap_or(ptr::null()), 1);
 	}
 }