Add more OpenGM inference algorithm options
enh: augment string parameter for algorithms by optional dict of kwargs
fix switch_to test.
Also, don't switch back after switching.
starting on potts example to compare inference methods
add ogm inference, use new dict interface for options
EXMPL three separate plots with increaslingly larger models in plot_inference_potts
add more inference algorithms
add non-submodular inference example, lp not tight here.