Peppercornenumerator

Removed setup.py, fixed flake8-detected bugs, bumping to Python>=3.8.

1.1 -- Mayor Python>=3.7 code cleanup and speedups for some core functions.
* rewrite of all objects to use dsdobjects>=0.8 (an attempt to fix rare segfaults).
* moved ratemodel related functions to peppercornenumerator/ratemodel.py.
* renamed open to open1N in order to avoid name conflicts.
* default concentration unit for output is now 'nM' throughout the library.
* updating and extending unittests.
* some pythonification of old code.
* removing deprecated code and undocumented experimental features.
* updated files in case_study directory for compatibility with changes.

Used for publication: https://doi.org/10.1098/rsif.2019.0866

Used for publication: https://doi.org/10.1098/rsif.2019.0866

- repository includes case studies from manuscript revision.
- update requirements of dsdobjects
- using logging module in a more standard way
- Python 3.x and Python 2.7 are still supported

A major update of the code.

- Python 3.x and Python 2.7 are now supported
- repository includes case studies from manuscript submission.
- update requirements of dsdobjects and crnsimulator
- added seesaw parser