WIP: Preparing the codebase, nothing important

Signed-off-by: Nikolai Rodionov <allanger@badhouseplants.net>

lib/src/region.rs

@@ -0,0 +1,11 @@
+use crate::metadata::Metadata;
+
+pub(crate) struct Region {
+    metadata: Metadata,
+    // Position of the track on the track
+    starts_at: u64,
+    // From which point of the audio source the region starts
+    plays_from: u64,
+    // Duration of the region after plays_from
+    duration: u64,
+}