Fixing a bug where himl flattens nested lists

[CameronDevine]

Description

In order to fix an issue where himl flattens nested lists, the DictIterator was modified.

Related Issue

#174

Motivation and Context

If a configuration file should have nested lists, himl is no longer compatible. This change allows himl to process configuration files structured in this way.

How Has This Been Tested?

New unit tests were added to verify that the updated DictIterator functions as expected.

Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• I have signed the Adobe Open Source CLA.
• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.