add ability to disconnect from midi controller

Author: dogatech

fe/src/midi-manager.js

@@ -63,6 +63,12 @@ class MidiManager {
     }
   }
 
+  async disconnect() {
+    this._midiInput.removeListener();
+    this._midiInput = null;
+    this._channelCallbacks = [];
+  }
+
   _setupListeners() {
     if (this._midiInput) {
       Object.entries(this._channelCallbacks).forEach(([channel, chanCb]) => {

fe/src/search-toolbar.js

@@ -57,6 +57,7 @@ class SearchToolbar extends AlertsMixin(BpmMixin(QueryMixin(SearchMixin(SearchOp
         <options-menu-item @click="${this.openMouseCoordsAlert}">Show Mouse Coordinates</options-menu-item>
         <options-menu-item @click="${this.openCommonMultiplesAlert}">Show Common Multiples</options-menu-item>
         <options-menu-item @click="${this.connectToMidiController}">Connect to Midi controller</options-menu-item>
+        <options-menu-item @click="${this.disconnectMidiController}">Disconnect from Midi controller</options-menu-item>
         <options-menu-item @click="${this.openAboutPageDialog}">About</options-menu-item>
         ${debugMode ? html`<options-menu-item @click="${this.showDevTools}">View Developer Tools</options-menu-item>` : ''}
       </options-menu>
@@ -434,6 +435,10 @@ class SearchToolbar extends AlertsMixin(BpmMixin(QueryMixin(SearchMixin(SearchOp
     midiManager.connect(this.settings.getString('midi.controllerName'));
   }
 
+  disconnectMidiController(e) {
+    midiManager.disconnect();
+  }
+
   searchOptionsChanged(x) {
     if (this.searchOptionsChanged.bpmRestrict != x.bpmRestrict ||
         this.searchOptionsChanged.keyRestrict != x.keyRestrict ||