Merge pull request #2879 from skirpichev/gh2877

Fix several subs issues with Float's
Added singularity finder for univarite rational functions
Merge pull request #2878 from rajaths589/fixWignerIssue

Fix Wigner Issue: float arguments to range() in gaunt(), racah(), wigner_9j()
Add steradian unit: solid angle
new_beta_function
added newline to end of two files
added newline to end of two files
Removed backup file
Indentation error
merge conflicts in gamma_function.py removed
Modified import headers and argindex
Indentation resolved
Changed eval to pass
test_beta_functions modified
import diff added
broke test removed
Merge conflicts for gamma_test file removed
Indentation corrected
-> Add argument interface test
-> Fix test failures in stats module