Issue with longdouble in numpy

[rpgoldman]

I have this in some code:

logarr = np.fromiter(loglist, np.longdouble, -1)

which causes problems when using the numpy stubs:

simple_model_kl.py:20: error: Module has no attribute "longdouble"

I think it's correct to just add

class longdouble(floating): ...

to __init__.pyi