Renamed ShaderEffectItem to ShaderEffect and some API changes.

Renamed ShaderEffectItem to ShaderEffect and some API changes.

The ShaderEffectItem was renamed to ShaderEffect to be consistent
with other QML element names. The GLSL uniform variable
qt_ModelViewProjectionMatrix was renamed to qt_Matrix which is
easier to type and remember. The GridMesh element was removed.
The mesh resolution is now specified simply with a QSize.
To make the transition easier, the old API will continue to work
for some time, but will output warnings if used. Eventually, I
will remove the old API completely.

Change-Id: Iec4f2aa624a2c76a7db6750c58f73dbcb316ab6a
Reviewed-on: http://codereview.qt.nokia.com/2270
Reviewed-by: Qt Sanity Bot <qt_sanity_bot@ovi.com>
Reviewed-by: Gunnar Sletta <gunnar.sletta@nokia.com>