MAINT: start 1.10-devel.

* Create 1.10.0-notes.
* Add 1.10.-notes to the generated documentation.
* Update version number in setup.py
MAINT: Change default inplace, ufunc(...,out=x) casting to same_kind.

There has been a warning of this change since numpy 1.7. numpy 1.10
is a good time to do it. The nanvar function needed a fix after the
change, and the tests and documentation are updated.
MAINT: Update pavement.py to 1.10.0.