Rule-based column formatting

[krlmlr]

Specify distinct formatting (e.g. different number of significant figures, avoidance of scientific notation) per column or per container

• Tag value during creation with num() or char() -- property of the data

• Apply formatting based on column name/type

  • Manually: collect_spec

  • Automatically: set option to container

Solved by documentation in #311, this is about automation. Really useful with #400.

[krlmlr]

This issue lives here, because rule-based formatting is applicable to all subclasses of tbl.