Changes that should be made someday:

* io rewritten to use internal writing capabilities of arrays
* distributions heavy use of extract and insert (could use fancy indexing?) -- but we should wait until we learn how slow fancy indexing is....)
* Use of old Numeric C-API.  Using it means an extra C-level function call, but ...
* Make use of type addition to extend certain ufuncs with cephes quad types
* Use finfo(foo).bar instead of limits.foo_bar
