ell cut fix.

[HTJense]

Should address #119 . Instead of loading and simply trimming the array, we create an empty array and fill it out entry-wise before trimming it to the desired lmin-lmax range.

Before fix:

>>> l, ps = pspy_utils.ps_lensed_theory_to_dict("cl_camb.dat", "Dl", lmax = 500, start_at_zero=False)
>>> l.shape
(500,)
>>> ps["TT"].shape
(500,)
>>> l, ps = pspy_utils.ps_lensed_theory_to_dict("cl_camb.dat", "Dl", lmax = 500, start_at_zero=True)
>>> l.shape
(502,)
>>> ps["TT"].shape
(502,)

After fix:

>>> l, ps = pspy_utils.ps_lensed_theory_to_dict("cl_camb.dat", "Dl", lmax = 500, start_at_zero=False)
>>> l.shape
(498,)
>>> ps["TT"].shape
(498,)
>>> l, ps = pspy_utils.ps_lensed_theory_to_dict("cl_camb.dat", "Dl", lmax = 500, start_at_zero=True)
>>> l.shape
(500,)
>>> ps["TT"].shape
(500,)