Added .ipynb and nbconverted- to git ignore file, so that .ipynb code explorations aren't synced.
Added core class definitions (Axes, TensorDict) to the __init__ file.
Currently all of the rest of the cylinder PEPS code, taken from the tensors-6 run in ipynb.
The tensor definitions used for the featureless_boson state are here. Still need to add package imports, etc. to folder system.