Addressing reviewer comments.

Removed special case handling from _kolmogn_DMTW as handled in _kolmogn.
Simplified _kolmogn_PelzGood as subtractive cancellation not an issue for the
 extra terms in K2, K3.
Added _log_nfactorial_div_n_pow_n(n) to compute log(n!/n**n).
Removed unneeded comments and/or code notived by reviewer.
Removed _kolmogn_LCK as not used.
Made some function docstrings compliant.

scipy/stats/_distn_infrastructure.py

@@ -1662,14 +1662,14 @@ def _ppf_single(self, q, *args):
             left = min(-factor, right)
             while self._ppf_to_solve(left, q, *args) > 0.:
                 left, right = left * factor, left
-            # left is now such that cdf(left) < q
-            # if right has changed, then cdf(rught) >= q
+            # left is now such that cdf(left) <= q
+            # if right has changed, then cdf(right) > q
 
         if np.isinf(right):
             right = max(factor, left)
             while self._ppf_to_solve(right, q, *args) < 0.:
                 left, right = right, right * factor
-            # right is now such that cdf(right) > q
+            # right is now such that cdf(right) >= q
 
         return optimize.brentq(self._ppf_to_solve,
                                left, right, args=(q,)+args, xtol=self.xtol)