Release 1.2.0

[rhpvorderman]

Release checklist

• Check outstanding issues on JIRA and Github
• Check latest documentation
  looks fine
• Create a release branch
  • Set version to a stable number.
  • Change current development version in CHANGELOG.rst to stable version.
• Merge the release branch into master
• Create a test pypi package from the master branch. (Instructions.)
  • Use build-wheels.sh to build the compiled C wheels.
• Install the packages from the test pypi repository to see if they work.
• Created an annotated tag with the stable version number. Include changes
  from CHANGELOG.rst.
• Push tag to remote.
• Push tested packages to pypi
• merge master branch back into develop.
• Add updated version number to develop
• Update the package on bioconda
• Build the new tag on readthedocs. Only build the last patch version of
  each minor version. So 1.1.1 and 1.2.0 but not 1.1.0, 1.1.1 and 1.2.0.