Support for writing WOD ASCII

[s-good]

Currently we can read WOD ASCII format but not write it. Writing the ASCII data is helpful as the AutoQC code expects data in this format.

Branch https://github.com/IQuOD/wodpy/tree/wodascii_writer has been created. A basic writing code is included in the wodpy directory.

This needs work before it would be suitable for merging into the master branch as functionality is limited.

[bkatiemills]

This would be a great addition; being able to make artificial profiles would be useful when testing AutoQC, rather than the fake profile objects we currently use to mock up data for tests.

What other features are you looking for here? Happy to get involved if that helps, or leave it to you if you've got time set aside for this. I'd also want to extend the unit testing suite to validate correct performance, and maybe slice write_wodascii up into separate functions for each header (easier to write, test and read that way, though that's a matter of opinion of course).

[s-good]

I don't expect to have any time to work on this in the near future. The improvements I was thinking of were mostly to add support for writing other metadata and variables. It could also do with having some code tidying done and the unit tests adding. I'm happy for you to work on this if you'd like, but otherwise we could just leave it sitting here until there's a requirement to work on it again.