Implemented reading of irit files

[markriegler]

Overview

Loading irit files is now supported.

Comment

Nltk is used to extract the control point and knot vector entries.

[clemens-fricke]

Please add the nltk package to the dependencies. This needs to be done in the README.md and setup.py files. I am not sure if this will fix all the errors, but it should fix a few.

[jzwar]

Please add the nltk package to the dependencies. This needs to be done in the README.md and setup.py files. I am not sure if this will fix all the errors, but it should fix a few.

As I said during your implementation, I am not a huge fan of adding nltk as a dependency. It is a very powerful tool, but we only use a tiny part of it.

I am not sure if you are still available for future changes, so I will take the liberty to merge your implementation into a separate branch and continue with a keyword-based approach.

[j042]

Great, thanks! now, only xml and iges left ;)