Add dual slider widget
Use minimum and maximum as defaults for low value and high value, respectively
unroll loops in paint and mouse events
Capitalize on new Atom update which reuses dead observer space.
Merge pull request #9 from nmichaud/feature-dual-slider

Feature dual slider
cleanup the DualSlider implementation
Make user attrs and events overridable
Update Include import
Remove old action handler on Slider
WIP commit for ast upgrade
wip commit
WIP commit
rename file to something more descriptive
Rename file to something more descriptive. Update instance creation.
Add a sentinel mixin class for declarative exceptions
Remove dead code. Fix a bug with line numbers on enamldef decorators.
Code cleanup. Set the name of storage members.
Cleanpup and update the compiler version
Remove dead code. The Resolver now does the heavy lifting.
Release the local scopes on operator teardown.