Add a built in plugin for flexible transformation of output format

[jgranstrom]

There should be a built in plugin that is configurable in order to produce different formats and structure of extracted output. This can for example be to extract numbers as strings that include the number unit, instead of parsing it to a javascript number type.

If you have any specific cases where you are currently required to modify the output format please include that use case here so that we can bake it in as a feature for a built in transformation plugin.

[vampics]

+1