Backporting QML ShaderEffectItem from QML2.0 into Qt Quick 1.1

This issue is about backporting Scenegraph's ShaderEffectItem element - http://qt.gitorious.org/qt-labs/scene-graph/blobs/master/src/effects/shadereffectitem.cpp into Qt Quick 1.1 as Qt labs plugin.

Purpose of ShaderEffectItem is to provide interface for utilizing OpenGL shaders in QML applications. When using the item applications need to use OpenGL ES graphics system of Qt.

The backported ShaderEffectItem is based on QGraphicsView wheras the ShaderEffectItem of QML 2.0 is based on SceneGraph.

Scenegraph's ShaderEffectItem will be productized as a part of the upcoming QML2.0, and its API may still evolve during QML2.0 development. The item is released as a Qt labs plugin rather than including it directly into QML 1.1.

Qt labs plugins are experimental extensions to QML. Existing plugins are e.g. particles, folderlistmodel and gestures.