public void registerBinding(String shaderName, final Filter filter) {
        registerBinding(new FileChangedTrigger(shaderName), filter);
    }
Will reload the filter's materials whenever the shader file is changed 
on the hard drive
@param shaderName the shader name (relative path to the asset folder or 
to a registered asset path)
@param filter the filter to reload
jme3-core/src/main/java/com/jme3/util/MaterialDebugAppState.java