[Lazarus] Flexible exporter for grid-like components

[Werner Pamler]

> Does not grid implies a 2D format?
> TLazGridTextExporter?
> TLazTextGridExporter?
> Is necessary Laz prefix?
Bart was talking of the ancestor of TGridExporter and TListviewExporter. 
No, the Laz prefix is not necessary; TExporter, on the other hand, is a 
very simple name which could exist in some other package already.