added an initAce hook to allow configuration of the live editor

lib/gollum/public/gollum/livepreview/js/livepreview.js

@@ -36,7 +36,6 @@ var MarkdownMode = require( 'ace/mode/markdown' ).Mode;
 
 function initAce( editor, editorSession ) {
   editorSession.setUndoManager(new UndoManager());
-  editor.setTheme( 'ace/theme/twilight' );
   editorSession.setMode( new MarkdownMode() );
   // Gutter shows line numbers
   editor.renderer.setShowGutter( true );
@@ -46,6 +45,11 @@ function initAce( editor, editorSession ) {
   editorSession.setUseWrapMode( true );
   editor.setShowPrintMargin( false );
   editor.setBehavioursEnabled( true );
+  if ( win.initAce ) {
+    win.initAce(editor, editorSession);
+  } else {
+    editor.setTheme( 'ace/theme/twilight' );
+  }
 }
 
 initAce( editor, editorSession );