Make array_view::operator= non-const
[examples] use np.radians/np.degrees where appropriate
fix typo

Signed-off-by: Thomas Hisch <t.hisch@gmail.com>
Merge pull request #3814 from thisch/radians

[examples] use np.radians/np.degrees where appropriate
Merge pull request #3813 from mdboom/non-const-operator=

Make array_view::operator= non-const