Tessellate

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* Pandas!
* Pandas dataframe output in json and csv is the default
* make Pandas default
* how to use a library example in the README
* biopython and pytest have different signatures beneath a certain version. Fixed this in setup.py
* removed hardcoded python interpreter, in some cases machine point to python2.7 with python3 pointing to 3. Remove in *.py files. Removed in Makefile. To use another python in the make file, modify the pythonexe variable
* Tested with --user flag. --user flag seems to work for me - e.g. pip3 install --user tessellate

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* Zenodo DOI
* empty list bug resolved
* feature order json output

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* Includes tcl script for VMD and example data

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* Documentation update. Ring finder update

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* Usecase, documentation update. Update requirements for PyPi

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* First release on PyPi