Modification of I_Io_calc for gcvspl

Modification of I_Io_calc
Adding IR_dec_comb, but not usefull for now
Update of spectratools.py
Changes for using gcvspl baselines

Changes have been made in the scripts in order to use the gcvspl
baseline instead of the univariate baseline.

Readme has been a little bit completed.

Spectratools.py has been modified. Now we can input directly x y
spectra with using gcvspl, which assumes in this case that the errors
are sqrt(y).
Merge branch 'master' of https://github.com/charlesll/RamPy

Conflicts:
	I_Io_calc.py