BUG: Explicitly reject nan values for p in binomial(n, p). Fixes #4571.

Adds check with np.isnan(p) and raises ValueError if check is positive.
Merge pull request #4587 from ddasilva/meltingwax/4571

BUG: Explicitly reject nan values for p in binomial(n, p).
ENH: Better error w/ line num for bad column count in np.loadtxt()

Resolves #2591. Adds more explicit error handling in line parsing loop.
Merge pull request #4588 from ddasilva/ddasilva/2591

ENH: Better error w/ line num for bad column count in np.loadtxt()
BUG: Prevent division by zero. Closes #650.
Merge pull request #4591 from szpy/bugfixes

BUG: Prevent division by zero. Closes #650.