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/mod.rs

@@ -45,7 +45,7 @@ pub use m2ts::M2tsStream;
 pub use mkvstream::MkvStream;
 pub use network::NetworkStream;
 pub use null::NullStream;
-pub use resolve::{open_input, open_output, open_pes_input, open_pes_output, parse_url, InputOptions, StreamUrl};
+pub use resolve::{input, output, open_input, open_output, parse_url, InputOptions, StreamUrl};
 pub use stdio::StdioStream;
 
 use crate::disc::DiscTitle;