Rename traj_2_graph to solutions_2_graph; Update doc; ability to take a directory instead of just 1 file

place => entity
frontier place => boundary
many variables that switch from snake_case to camelCase
=> induces many problems of uniformity in the API and is very confusing; have fun.

sphinx-argparse module requires the object parser before the call of parse_args()

Add an entry to the command line: sol_digging to decompile each transition in a complete solution file

Ability to dump tests results in json file; graph_isomorph_test() returns a check dict for easy integration in python scripts