Modify extension could handle added/deleted items

[agios]

There already seems to be some thought for it, assuming that the opt.type=0 parameter in core/model/extensions/Modify.js#set was meant to be used for that purpose.

Is there some reason it was never implemented, or is someone working on it? Otherwise I could maybe take a look at it, although new to Dojo, and JavaScript for that matter.

[agios]

This is an initial implementation, it works in my tests. Also changed how save behaves, it now deletes lazy data only for rows where the save succeeded, so if some server validation fails you do not lose your work in progress.

What do you think?

[yurychika]

agios, thanks for the pull request. You are right that we plan to implement the lazy add and delete functionality.

While we are in the process of releasing gridx 1.3, after the release I will review your code and work with the team on that feature.

Thanks again for using and contributing to gridx.