README.dev

It is sometimes difficult to get a stable requirements.txt that would work
for developers, travis and readthedocs.

This file can be used to provide reasons for pinning some package versions.


- ruamel.yaml add ruamel.yaml inside setup.py instead of requirements.
  Since Feb 2018, ruamel.yaml in the requirements fails on travis with this
  error::

    UnsatisfiableError: The following specifications were found to be in conflict:
        - python=3.5
        - ruamel_yaml -> python[version='>=3.6,<3.7.0a0']
    Use "conda info <package>" to see the dependencies for each package.


  looks like there is ruamel.yaml, ruamel_yaml and conflicts between conda,
  conda-forge, bioconda. Wierd that it works for py36 though.

  so only solution so far is to install ruamel.yaml with pip in .travis and
  therefore to remove it from the requirements.txt