Unified Stream trait: read() and write() on one type

Stream trait: read() returns PesFrame, write() accepts PesFrame.
A stream is a stream — you read from it or write to it.
No separate Input/Output traits.

API: libfreemkv::input(url) and libfreemkv::output(url, title, codecs)
Returns Box<dyn Stream>.

src/mux/ps.rs

@@ -82,7 +82,6 @@ impl PsDemuxer {
         let mut pos = 0;
 
         while let Some(sc) = find_start_code(&self.buffer, pos) {
-
             if sc + 3 >= self.buffer.len() {
                 // Not enough bytes to read the start code ID.
                 break;