wip: init shared jack clients

crates/tek_sequencer/src/arranger.rs

@@ -2,6 +2,8 @@ use crate::*;
 
 /// Root level object for standalone `tek_arranger`
 pub struct Arranger<E: Engine> {
+    /// JACK client handle (needs to not be dropped for standalone mode to work).
+    pub jack:              Option<Arc<JackClient>>,
     /// Which view is focused
     pub focus_cursor:      (usize, usize),
     /// Controls the JACK transport.
@@ -121,7 +123,8 @@ impl<E: Engine> Arranger<E> {
         phrases:     Arc<RwLock<PhrasePool<E>>>,
     ) -> Self {
         let mut app = Self {
-            focus_cursor:  (0, 1),
+            jack:              None,
+            focus_cursor:      (0, 1),
             phrases_split:     20,
             arrangement_split: 21,
             editor: PhraseEditor::new(),