improved six Jc functions: 1) functions are 10-60% faster now. 2) function Jc_NbTi_Bottura.m cannot return imaginary values anymore

fixed a second bug in the recently changed cpNb3Sn_Arp_Knapp_mat.m, which gave an error if the argument T was an empty vector

fixed bug in the recently changed cpNb3Sn_Arp_Knapp_mat.m, which gave an error if 4 empty arguments were passed

Improved the function cpNb3Sn_Arp_Knapp_mat.m: 1) it now works when Tc, Tc0, Tcs are either scalars or vectors. 2) if Tc, Tc0, and Tcs are all vectors with identical elements. If so, they'll be changed to scalars to speed up calculation. 3) Small speed improvement by commenting redundant "ps(idxAboveTc) = 0;". 4) changed code reformatting to make it more readable. NOTE: The edited function is expected to return the same values as before (when Tc, Tc0, Tcs are scalars).

renamed Matlab functions cpNb3Sn_cryocomp_mat and cpNb3Sn_cryocomp_B to cpNb3Sn_Arp_Knapp_mat and cpNb3Sn_Arp_Knapp_B

CFUN_CvNb3Sn_Arp_Knapp_v1 function is deprecated!

corrected STEAM_MatPro_template.m to correctly write handle_Tc_Tcs_Nb3Sn_Bordini and handle_Tc_Tcs_Nb3Sn_Summers

fixed bug in rhoBeCu_nist_mat.m that caused an error when the argument f_scaling is a scalar (which should be the only way the function works...)

- Added example 10.

- updated the requirements.txt
- made a small change to the STEAM_materials.py package, as it would not accept lists anymore.