Change guess of transmissive standard in TwelveTerm.
Change guess of transmissive standard in TwelveTerm.

Guessing of which stds are transmissive was done using a criteria
in dB. When S21 in a std is 0 for some values and you compute dB(s21)
then you get warnings. Changed criteria to do comparison in magnitude
instead.

jhillairet/scikit-rf,temmeand/scikit-rf,jhillairet/scikit-rf,temmeand/scikit-rf,scikit-rf/scikit-rf,Ttl/scikit-rf,Ttl/scikit-rf,Ttl/scikit-rf,Ttl/scikit-rf,jhillairet/scikit-rf,scikit-rf/scikit-rf,temmeand/scikit-rf