Add configuration arguments for trimming content

[GhaTMA]

New Feature Request!

People tend to use tabs/whitespaces in CSV file to make them more readable. This makes a problem when the content cells are not delimited. Because those characters would be included as content which was not the initial intention of those users. It would make sense to let the parser trim the content of leading and trailing tabs/whitespaces. Best way to do it IMHO is to provide an additional configuration argument for this purpose.

[xlson]

I'm not actively developing GroovyCSV any more but if I get a PR for this functionality I will merge it and release a new version of the library.