removed glContext parameter from method calls since it can be accessed from global application if required
removed usage of _appInstance and replaced it with a static Application::instance() call, moved test ui creation into UiTestApp, started work on deferred render queue and compositing, Layers now request redraw upon creation, added needsRedraw() method to Layer, UserInterface and RenderSystem, View now uses ViewPtr as const&
added visibility and sublayer checks
added guard in case no rootView is present
disabled old draw code, started prepareRedraws and layer caching, still needs some ground work