Unified cell range model for CSV Layouts

[georg-schwarz]

Currently, the concept to describe CSV files is column-based. We assume that this does not live up to the complexity of CSV files in practice. Thus, we need a concept based on cell-ranges (as a more generic way) to describe CSV files.

The current syntax might be syntactic sugar, e.g. column A: text; might be a short form for range (A:A): text.

Tackling this issue might require redesigning the whole sheet concept, as cell ranges might overlap etc.