Don't use evaluate kwarg for eval methods: fix catalan and euler functions

fixes #8496
fix issue #8323

	harmonic(n).evalf() and catalan(n).evalf()
Implement Mod._eval_is_integer helper for assumptions

fixes #8486
Merge pull request #8498 from skirpichev/8496-fix

Don't use evaluate kwarg for eval methods: fix catalan and euler
Merge pull request #8371 from zanzibar7/evalf_harmonic_and_catalan

fix issue #8323
correct pep8
refine convert functions from atan2 to atan if the sign is defined
Merge pull request #8497 from skirpichev/8486-fix

Implement Mod._eval_is_integer helper for assumptions
Merge pull request #8484 from jfosorio/atan2_refine

New refine entry for the atan2 function
Falling and Rising factorials are integers
Merge pull request #8493 from pelegm/rf_ff_are_integers

Falling and Rising factorials of integers are integers