Sneak preview: cell edit api to support commit-on-focusLost

[Jeanette Winzenburg]

Hi folks,

after fixing a bunch of edit-related issues, time feels right for  
nudging elephant out of the room :) Which is the bigger goal of  
supporting commit-on-focusLost.


Working on a PoC (ListView/-Cell only) in a branch of my fork   
https://github.com/kleopatra/jfx/tree/dokeep-edit-api-editstate with  
an overview of suggested changes  
https://github.com/kleopatra/swingempire-fx/wiki/CellEditAPI and a  
example driver as gist  
https://gist.github.com/kleopatra/447344183e017537c21f7905a062396d

Still rough, but working: all current unit tests still passing (a  
bunch of my own not, and the new api is barely tested) and many of the  
requested requirements can be implemented (see code in the example and  
the table of use-cases in the overview)

Any feedback - for the good or for the bad - highly welcome :)

-- Jeanette