NodeUtils: allow YAML list to declare node groups

[griznog]

Allow the use of YAML list syntax when defining node groups.

[degremont]

Thanks for your patch. It looks good, could you also:

• Add a test for that in tests/NodeSetGroupTest.py, at the end of YAMLGroupLoaderTest class
• A tiny example in the doc in doc/sphinx/config.rst

Could you also edit your commit message and make it looks similar to 9b3a239 by example, meaning:

• A title with a prefix : NodeUtils:
• A small title (less than 70 char): allow YAML list to declare node groups
• A blank line
• A sentence explaining the change more in detail

[degremont]

Thanks for the changes. They looks good! However, when I was talking about the commit message, I was really talking about the commit message of the unique commit you should have in this branch.
Could you squash all your 4 commits together in 1 and update the commit message as explained previously?

[griznog]

Clearly I'm lost with the git squash part of this, I don't understand why I wound up with the second merge commit? Lots of "first time doing X" for me in this process, thanks for being patient.

[thiell]

Hey thanks @griznog! Getting ready for your cluster of tractors? ;-)
We'll be able to squash the commits for you when merging, no worries.

[degremont]

Thanks @griznog , I managed the squash things. Thanks for your patch!
If you want to know more about squashing, for next time ;) : https://stackoverflow.com/questions/5189560/squash-my-last-x-commits-together-using-git

[griznog]

Hey thanks @griznog! Getting ready for your cluster of tractors? ;-)
We'll be able to squash the commits for you when merging, no worries.

I'm hoping to keep my squash in the garden :)