add a buffer object for variance shadows
add shaders to perform the variance light shader depth packing
add a model class for the variance light shader, and an empty 568h default png
refactor away the properties, instantiate the variance light shader
add a model class for the variance shadow shader
implement the variance shadow mapping shader
add an FBO base class to enable switching between the two buffer types
add a segmented control to change the shadowing technique
remove mipmapping for now
don’t use full shadows in the variance shadow map