state: persist the queue and pick up where playback stopped

The queue, its shuffle order and whether playback was running are written to
~/.local/state/rsplayer/state.json whenever they change, and on shutdown, then
restored at daemon start. Tracks that disappeared from disk are dropped
instead of failing on play.

`rsp resume`/`rsp toggle` now start the restored track when nothing is loaded
into the engine yet, which is the state right after a restart with a queue
that was paused.

1 files changed, 1 insertions, 0 deletions

diff --git a/src/lib.rs b/src/lib.rs
index f08e8ea..189c376 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -22,3 +22,4 @@ pub mod notification;
 pub mod playback;
 pub mod queue;
 pub mod scrobbler;
+pub mod state;