Add persistent accessibility pane

This will facilitate more extensive usage of the menu than the
context menu.

src/extension.ts

@@ -3,6 +3,8 @@ import * as vscode from 'vscode';
 import * as pl from './pylex';
 import commands from './commands';
 
+import { AccessNodeProvider } from './accessNodeProvider'
+
 let parser: pl.Parser = new pl.Parser();
 
 export function activate(context: vscode.ExtensionContext) {
@@ -19,6 +21,10 @@ export function activate(context: vscode.ExtensionContext) {
     );
     context.subscriptions.push(disposable);
   });
+
+  let provider = new AccessNodeProvider();
+  vscode.window.registerTreeDataProvider('accessActions', provider);
+
 }
 
 export function deactivate() {}