Modes of variability (branch: 377 variability mode nao)

[lee1043]

Work in progress for merging the modes variability code to the master. Please do not merge yet. The PR is not ready for merging until told by myself.

[lee1043]

@muryanto1 I think the code is ready for merging, could you please take a look when you have time? Thank you very much!

[muryanto1]

test passed. Note that I am approving this PR to be merged just based on the fact that it does not break existing tests. I did not review the content of the changes as that will require me to understand the project, and my time will not allow me at this moment.
Looking at a glance, I have following questions:

• why are there *py under pcmdi_metrics/variability_mode/doc directory? I assume 'doc' is for documentations.
• If those *py code are supposed to run somewhere, it has hardcoded directory /work/lee1043, I am guessing that the code will fail if you run it on a machine that does not have access to that dir.
  Similarly, it has hardcoded /p/user_pub/PCMDIobs/...

[lee1043]

@muryanto1 thank you for reviewing the PR.

• doc directory is for parameter files that serve as a namelist example, collecting user given options such as directory to find input data. Thoes parameter codes are not running by themselves but always working with *py in scripts directory.
• I agree directory name could be better name than 'doc'. But at the moment what I need to be done is placing code in the master branch for PCMDI SFA proposal, so I will think about it later.

[lee1043]

@gleckler1 MoV code is in master now. As we discussed earlier we will need to work on documentation, usage example, and test suites.