Addressed inability of python wrapper to handle mulitple chimesFF instances

[JaredStimac]

Changes to the python wrapper that allow for multiple chimesFF instances. I found that for a single system call, I could not modify chimes parameters or atom labels as the chimesFF instance would persist and could not be reset.

This is accomplished by creating additional python wrapper functions that calls the "instance" versions of functions within chimescalc_serial_C.cpp. All of the previous python wrapper functions are unchanged to maintain backwards compatibility.

This might address issue #67 (OOM errors when use ChIMES calculator Python serial interface multiple times). You should be able to prevent OOM by calling chimes_close_instance(), as is done in python_instance/main.py

run_tests.log

[rk-lindsey]

@JaredStimac could you please update the documentation so users know when/how to use this functionality? See, e.g., this page.