Zero source

[davidrandell84]

Description

Extending pyelq to enable zero sources. The main changes are are in open_mcmc this is a matched PR to catchup the changes.

Fixes # (issue)

Type of change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)
• [x ] New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

Jupyter Notebooks

If your changes involve Jupyter notebooks please explicitly state here what the change consists of, e.g. only output cells have changes or specific input changes. This to make sure we capture these changes correctly in the review process.

How Has This Been Tested?

No changes to tests but the example basic notebook has been extend to include the zero source case.

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my code
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• [ x] Any dependent changes have been merged and published in downstream modules