Map cells

[MagicMuscleMan]

include accepts a mapexpr::Function argument to transform the included code. It would be useful if such a mapexpr::Function would also be available when reading a CSV file. The mapping should probably be done before the column type is automatically determined, but this might need some more thinking from someone familiar with the code.

A typical use case would be that a column contains a value and a unit and needs some code to create the necessary object. But it could be used for all sort of validation / object creation.