Create package structure

[ ] Create top level folder gc_derivatization
[ ] Move code from gx_meox_tms.py into __main__.py in the package folder
[ ] Extract library functions into respective files (utils.py, plot.py, derivatization.py)
[ ] Create correct imports in __init__.py file
[ ] Fin out differences between setup.py file for package and setup.cfg

RECETOX / gc-meox-tms