romspline converted to python3

romspline/__init__.py

romspline/build_spline.py

romspline/convergence.py

romspline/cross_validation.py

romspline/example.py

romspline/greedy.py

romspline/h5splinetotxt.py

romspline/helpers.py

romspline/random_seeds.py

romspline/regression.py