[Kst] [Bug 130195] New: Datasources should enforce field unicity

[Brisset, Nicolas]

> This is definitely datasource specific, so it sounds like you 
> want this bug report to apply to the ASCII datasource.  For 
> the healpix and the new FITS datasources, I solve this 
> problem by simply prepending an absolute field number to the 
> text of the field name.  
Sure, that's an option. The only thing I don't so much like about this
is that you may end up having to hand-edit all legend texts, while it is
sensible to expect that (untransformed) variable names are quite often
the best legend text. What I'd rather do is: transform only names that
are already taken, with the issue that I don't want to slow things down
too much. Name lookup would need to be fast in case the user has very
many variables (I know some who have thousands...), if some of you have
ideas (or reusable code) to do that, it could be interesting :-)

Nicolas