Driver: Reduce logging level in general (#48)

This change reduces many log levels to debug, particularly where errors are likely to be triggered by undocumented Discord messages or by threads exiting in an unpredictable way. This also reduces the task entry/exit messages to `trace`.

This PR has been tested via `cargo make ready`, and by manually inspecting logs at `debug` and `info` levels running `examples/serenity/voice`.

src/driver/tasks/mixer.rs

@@ -22,7 +22,7 @@ use std::time::Instant;
 use tokio::runtime::Handle;
 #[cfg(feature = "tokio-02-marker")]
 use tokio_compat::runtime::Handle;
-use tracing::{error, instrument};
+use tracing::{debug, error, instrument};
 use xsalsa20poly1305::TAG_SIZE;
 
 pub struct Mixer {
@@ -111,8 +111,6 @@ impl Mixer {
         'runner: loop {
             if self.conn_active.is_some() {
                 loop {
-                    use MixerMessage::*;
-
                     match self.mix_rx.try_recv() {
                         Ok(m) => {
                             let (events, conn, should_exit) = self.handle_message(m);
@@ -138,7 +136,7 @@ impl Mixer {
                     events_failure |= e.should_trigger_interconnect_rebuild();
                     conn_failure |= e.should_trigger_connect();
 
-                    error!("Mixer thread cycle: {:?}", e);
+                    debug!("Mixer thread cycle: {:?}", e);
                 }
             } else {
                 match self.mix_rx.recv() {