First attempt at integrating a Ginga viewer into Glue
Updates to ginga viewer option

- now uses the icons for the toolbar and exclusive mode for tool choice
- improvement in rendering speed of redraws with data subsets
Small updates
Changed to using image overlays feature
Further partial updates
Extract mpl-agnostic base class out of ImageClient
First-pass refactor of Ginga into glue-style artist layers
CLeanup
After client/artist reorg fixes for ginga viewer

- fixed delete layer (except base data layer)
- fixed visibility layer (except base data layer)
Improved toolbar, now closer to regular Image Viewer
First attempt at integrating a Ginga viewer into Glue
Updates to ginga viewer option

- now uses the icons for the toolbar and exclusive mode for tool choice
- improvement in rendering speed of redraws with data subsets
Small updates
Changed to using image overlays feature
Further partial updates
Extract mpl-agnostic base class out of ImageClient
First-pass refactor of Ginga into glue-style artist layers
Cleanup
Rename ax->axes
Pull mpl-agnostic code into ImageWidget base class