Replace warning_exit by ValueError
BUG-FIX: MVATools.decompositon, MVATools.normalize_poissonian_noise and misc.eels.tools.estimate_noise_variance where assuming that after unfolding the fist data axis was the navigation axis what is not generally true. Added decomposition tests.
Merge pull request #115 from francisco-dlp/BUG-FIX_wrong_unfolded_assumption

Bug fix wrong unfolded assumption