Merge pull request #158 from to266/chi_squared

Chi squared
Fix Fourier ratio default treshold

EELS.fourier_ratio_deconvlution bug: Docstring say default treshold of
None should make method use first minimum. The feature was not
implemented, and caused an exception in
estimate_elastic_scattering_intensity. Fixed by calling
elastic_scattering_treshold if treshold is None.
Merge pull request #227 from vidartf/VidarsBranch

Fix Fourier ratio default treshold
Merge branch 'master' of https://github.com/hyperspy/hyperspy into signal_variance_inav

Conflicts:
	hyperspy/signal.py
Automatic style corrections courtesy of autopep8
fixed to pass varience as required with new metadata structure
Automatic style corrections courtesy of autopep8
removed unnecesarry commented lines
Merge branch 'signal_variance_inav' into parafit