Add Function to get column by name

[123FLO321]

Adds a function that find and returns a column with a given name

[mbarnach]

That's something I've written myself many times! A great addition I think!

[CLAassistant]

Thank you for your submission! We really appreciate it. Like many open source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution.
_{You have signed the CLA already but the status is still pending? Let us recheck it.}

[mbarnach]

@123FLO321 Any chance you can add a test for this function? Maybe in TestAlias.swift?