Tidy lagrange_wfasm_test_exp

 - make gen_dirichlet_exps_codes back as a function
Change polygon_2d.py that is in terse_demo using Polygon2D in terse_proto
Add plot_jpolygon method in polygon_2d_util

 - demo in polygon_2d_util seems right
rename variable 'vs' to 'act_vs' in polygon_2d_util in terse_demo
add timoshenko_process_demo to plot and show the Timoshenko example