Call simplify() in Add._eval_as_leading_term.  Fix issue 3265.
Extract nested Order expr
Handle NotImplementedError in Pow.nseries
Merge branch 'master' into 3265-eval-lt-fix
remove assert
remove obsoleted stuff in power.py
Add logx defaults
Merge branch 'master' into 3265-eval-lt-fix
Revert "Handle NotImplementedError in Pow.nseries"

This reverts commit 17d61527faa736497b4a2ff37cb6345b93f2a601.
A better handling for rest=0 case
Cleanup prefactor calculation
Merge branch 'logx-clean' into 3265-eval-lt-fix
Merge branch 'master' into 3265-eval-lt-fix
O(1) -> O(1, x)
Merge pull request #2500 from skirpichev/3265-eval-lt-fix

Fix issue 3265 (simplify output of Add._eval_as_leading_term)