Add GABA as Reference spectra example

[DJ]

Hi,

I put on the GitHib a new reference spectra example. That's the GABA compound acquired with a Bruker Advance II instrument, with different analytical parameters, 1D (1H & 13C) and 2D (1H/13C, 1H/1H). The analytical parameters file and peaks list file are provided too. Hope this can serve as an complete example.

Cheers,

DJ