Important changes to simplify traitlets....
Important changes to simplify traitlets.
Some aspect of traitlets were a bit too magical for us. Thus, we have
simplified certain things to make it more straitforward:
* Default values are always validated, but now, this is done when
the HasTraitlets.__new__ is called. We used to do this the first
time __get__ was called.
* The klass argument of Type and Instance traitlets must be a class.
Unlike enthought.traits, we are no longer accepting class names as str
or instances.
* The args and kw arguments to Instance.__init__ are now handled in
better manner, but that is quite different from enthought.traits.
* More tests of edge cases.
