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
Hoist constants out of loops.
more code factorisation
Issue 3994 fix
Merge branch 'master' into 3265-eval-lt-fix
O(1) -> O(1, x)
4094: add note about chop

While checking this I noticed that chopping occurs for
any number in an expression, not only the final result.
This is sub-optimal. e.g. (pi/65).n(chop=.01) rounds to
zero because the 1/65 rounds to less than 0.02 and is
replaced with zero even though if the rounding was delayed
until the multiplication by pi occured, it wouldn't have
been rounded. I did not clutter the docs with this detail, however.
Merge pull request #2576 from smichr/docs

4094: add note about chop in docs
preserve shape for 0-sized Matrices