Adds magnifier functionality to gnome-shell.

Adds the ability to create one or more zoom regions that show magnified or
enhanced views of the desktop.  The magnifier provides options for:
* magnification factor,
* four mouse tracking modes common to screen magnifiers,
* positioning the magnified view in one of four screen location, or full screen,
* crosshairs to accentuate the position of the mouse,
* user preferences persistence via GConf (schemas in
  .../data/gnome-shell.schemas).
* a DBus API to allow other processes to drive the magnifier as a service.

https://bugzilla.gnome.org/show_bug.cgi?id=595507

js/ui/Makefile.am

@@ -17,6 +17,8 @@ dist_jsui_DATA =		\
 	link.js			\
 	lookingGlass.js		\
 	main.js			\
+	magnifier.js		\
+	magnifierDBus.js	\
 	messageTray.js          \
 	notificationDaemon.js   \
 	overview.js		\

js/ui/main.js

@@ -26,6 +26,7 @@ const WindowAttentionHandler = imports.ui.windowAttentionHandler;
 const ShellDBus = imports.ui.shellDBus;
 const TelepathyClient = imports.ui.telepathyClient;
 const WindowManager = imports.ui.windowManager;
+const Magnifier = imports.ui.magnifier;
 
 const DEFAULT_BACKGROUND_COLOR = new Clutter.Color();
 DEFAULT_BACKGROUND_COLOR.from_pixel(0x2266bbff);
@@ -46,6 +47,7 @@ let shellDBusService = null;
 let modalCount = 0;
 let modalActorFocusStack = [];
 let uiGroup = null;
+let magnifier = null;
 let _errorLogStack = [];
 let _startDate;
 
@@ -162,6 +164,9 @@ function start() {
 
     global.stage.connect('captured-event', _globalKeyPressHandler);
 
+    // Install magnifier.
+    magnifier = new Magnifier.Magnifier();
+
     _log('info', 'loaded at ' + _startDate);
     log('GNOME Shell started at ' + _startDate);