[Kst] Tribute to kst's power

[Brisset, Nicolas]

> [benchmark done on a P4 PC @ 3GHz with 2GB RAM, with version 
> 1.1 as far as I can remember]
> - 12 vectors * 2 932 000 samples
> - 9 power spectra * 4194304 points
> - 9 histograms with 150 bins on the 2.9 Mpoints vectors
> 
> 2 min 30 s to load the .kst file
> zoom refreshes in less than 1s
> 3 s to resize a window with 3 simple plots
> 5 s to resize a window with 3 power spectra in lin-log axes
Oh, I forgot to mention that the data was in a plain text file, whose
size is no less than 315 Mbytes !