added square lena for testing
docs & pep8
add WithCallbacks
better names
merge WithCallback
 added layout
yoink_cmap -> 2 figs + lib changes
WithCallbacks -> textbox to avoid circular dependencies
add NothingWidget
rename DragableCmap to DragableColorLine
simplify remove Cmap stuff from DragableColorLine
add ScaledCmap
add RecoloredWidget
major udpate to yoink_cmap
import partial