Support ColumnIgnore Attribute, or add an overload to ColumnHeader to ignore fields from the output

[cajuncoding]

It's a very common use case to have Models that have additional fields that we don't wish to output such as what is provided by JsonIgnore attribute for Json. For the Spreadcheetah outputs we don't always want to spin up new models just to hide fields so a feature to support this would be very useful. It could be a new [ColumnIgnore] attribute or an overload on the existing [ColumnHeader] attribute. Along with some additional examples in the docs to show these additional features for the CodeGen functionality. 😁

[sveinungf]

Sounds like a useful feature. Thanks for the suggestion!

[sveinungf]

The ColumnIgnore attribute is now available in version 1.19.0. An example can be seen in the wiki.