#22 Multi columns definition edition

[Thierry Excoffier]

There is yet a raw (rude) way to import and export columns definitions in the 'Table/Action' tab. But it does no allow to modify columns definitions.

It will be nice to have a way to edit all the columns and all their attributes in a single table. It allows to have a global view, making easier to find problems.

A virtual table can be used.