single colour rendering of plot_block_model() + colorbar #269
Description
It generates a homogeneous blue block and we cannot see the stratigraphy!
e.g. https://loop3d.org/LoopStructural/_auto_examples/1_basic/plot_2_surface_modelling.html#sphx-glr-auto-examples-1-basic-plot-2-surface-modelling-py
Should some parameters be provided to display the stratigraphy?
In addition, the 'show_scalar_bar' parameter of the api is not recognised. I get a TypeError: plot_block_model() got an unexpected keyword argument 'show_scalar_bar'