Rewrite audio engine: replace BASS with miniaudio

SFX and blip players largely remain the same.

For the music player, we now have to implement network streaming
natively, we no longer have a convenient function that did everything
for us. I introduced QNetworkRequest to download the stream in memory
and signal when it's ready to be decoded and played back. The size is
guarded to prevent the client from accidentally downloading terabytes of
audio.

Delete QFutureWatcher, we no longer need it for concurrency. miniaudio
uses a separate audio thread. Network donwloads and communication with
the track name display are handled by Qt signals.

Also, delete an odd "music.txt" feature. Its purpose was specifying
offsets for loops in a text file per track, but it remained obscure and
unused in practice.

Unsupported:

- Large streams, including unbounded ones (radio). We'll need a ring
  buffer for that, and a mechanism to write to it from the network and
  feed it to the audio thread.

- Effect flags: fade in, fade out, sync pos. Ignored.

- Audio device selection.

1 files changed, 2 insertions, 0 deletions

diff --git a/src/networkmanager.h b/src/networkmanager.h
index 8f2d8d4..31b046d 100644
--- a/src/networkmanager.h
+++ b/src/networkmanager.h
@@ -40,6 +40,8 @@ public Q_SLOTS:
   void request_document(MSDocumentType document_type, const std::function<void(QString)> &cb);
   void send_heartbeat();
 
+  QNetworkReply *get_audio_url(const QUrl &url);
+
 Q_SIGNALS:
   void server_connected(bool state);