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>.

Cargo.toml

@@ -31,3 +31,7 @@ libc = "0.2"
 [target.'cfg(target_os = "macos")'.dependencies]
 libc = "0.2"
 
+[[bench]]
+name = "sgio_read"
+harness = false
+