Fix hidden panes: remove duplicate se-pane wrapper from PaneCP and PaneSubObjects

AppShell already wraps each component in div.se-pane; the inner se-pane
had display:none without .active, hiding all content.
Also drop stale movement/part/line/measure bar fields (bar IDs are opaque).

static/components/PaneCP.js

@@ -41,7 +41,7 @@ export const PaneCP = {
             const model = store.scoreModel;
             const fp = store.focusPath;
 
-            return h('div', { class: 'se-pane' }, [
+            return h('div', null, [
                 // Header
                 h('div', { class: 'se-cp-header' }, [
                     h('span', { class: 'se-cp-title' },