float128 vs. float64 issue in free spectrum createGWB

[bencebecsy]

Trying to inject a free spectrum GWB with userSpec in createGWB gives the following error on line 813 of toasim.py:

--> 813             hcf = 10.0**fspec_ex(N.log10(f))
TypeError: Cannot cast array data from dtype('float128') to dtype('float64') according to the rule 'safe'

It might be related to this old issue: #7

I managed to solve this in my local copy by inserting a line converting f to float64 before line 813:
f = N.float64(f)
but I'm not sure if this is the ultimate desired solution here.