Stabelize Network again:

- completly switch to Bytes, even in api. speed up TCP by fak 2
 - improve benchmarks
 - speed up mpsc metrics
 - gracefully handle shutdown by interpreting Ok(0) as tokio::tcpstream closed now.
 - fix hotloop in participants by adding `Some(n)` to fix endless handing.
 - fix closing bug by closing streams after `recv_mgr` is shutdown even if now shutdown is triggered locally.
 - fix prometheus
 - no longer throw when a `Stream` is dropped while participant still receives a msg for it.
 - fix the bandwith handling, TCP network send speed is up to 1.5GiB/s while recv is 150MiB/s
 - add documentation
 - tmp require rt-multi-threaded in client for tokio, to not fail cargo check

this is prob stable, i tested over 1 hour.
after that some optimisations in priomgr.
and impl. propper bandwith.
Speed is up to 2GB/s write and 150MB/s recv on a single core

sync add documentation

server-cli/src/logging.rs

@@ -17,7 +17,9 @@ pub fn init(basic: bool) {
         env.add_directive("veloren_world::sim=info".parse().unwrap())
             .add_directive("veloren_world::civ=info".parse().unwrap())
             .add_directive("uvth=warn".parse().unwrap())
-            .add_directive("tiny_http=warn".parse().unwrap())
+            .add_directive("hyper=info".parse().unwrap())
+            .add_directive("prometheus_hyper=info".parse().unwrap())
+            .add_directive("mio::pool=info".parse().unwrap())
             .add_directive("mio::sys::windows=debug".parse().unwrap())
             .add_directive("veloren_network_protocol=info".parse().unwrap())
             .add_directive(