Wp8 v3 fix for precompiled shaders and precompiled headers

This pull request updated the precompiled shadersfor WP8. Precompiled headers have also been restored.

Fixed GLProgram::link() for WP8. Note: WP8 does not support glBindAttribLocation() since we cannot call glLinkProgram() on a precompiled shader.

Note: The shaders for shadertest and 3D sprites will be in a separate pull request.