Adding simple mouse interaction to ViewBox + TwoDCamera
a bit closer
fixed entity_transform method
Mouse interaction working for TwoDCamera
Merge branch 'scenegraph' into mouse_interaction

Conflicts:
	vispy/scene/cameras.py
	vispy/scene/canvas.py
	vispy/scene/entity.py
	vispy/scene/events.py
	vispy/scene/viewbox.py
	vispy/scene/visuals/line.py
	vispy/scene/visuals/visual.py
flakify
docstrings
Removed print statements
Entity.__repr__ hides name if it has not been set
Fix Line.__init__ args
Fix Visual.__init__ args
Merge remote-tracking branch 'vispy/scenegraph' into mouse_interaction

Conflicts:
	vispy/scene/visuals/line.py
flakify
py3 fix
py3 style corrections
more py3 fixes
last py3 fix
Add flake3 makefile target
Merge pull request #281 from lcampagn/mouse_interaction

Mouse interaction
Added RegularPolygonVisual and example, refactored and optimized EllipseVisual