Added old kramers_kronig_transform and bethe_f_sum methods from BetheFSR branch
Modified kramers_kronig_transform to use Image inputs as integral of the ZLP
Modified kramers_kronig_transform to output thickness and mean free path
Fixed bug in kkt: the thickness formula was wrong because of energy scale factor in the integral
Added a file to put kramers_kronig_transform related tests
Fix energy scale bugagain when ZLP has to be summed
Improved documentation of Bethe-f-sum rule
Bug-fixed the conditional output of kramers_kronig_transform
Improved nose-tests for kramers_kronig_analysis and bethe_f_sum
Added thickness nose-test for kramers_kronig_analysis
 Added the option to use a np.ndarray as input ZLP integral, useful for line EELSSpectra, as there are no 1D images in hyperspy
Fix bug when doing KKA with single spectrum and input ZLP integral was single float number
Merge branch 'master' into fix_kka
Added option to KKT: delta input for energy instability, follows Egerton matlab code
KKT: set default delta parameter to 0.05
Improved KKT documentation
Added thickness normalization to KKT
Merge branch 'fix_kka' of https://github.com/AEljarrat/hyperspy into fix_kka
BUG-FIX: some KK tests were broken
Add DielectricFunction signal, rename KK to kramers_kronig_analysis, modify the tests accordingly and add user guide test. This is a partial commit, KK is not yet fully working.