readOnly rows implemented.

[0xMarK]

Now there can be some values that cannot be checked/unchecked. Their
initial selection state will remain read-only.

[alexleutgoeb]

Thanks for your pull request. I'm not sure if this is a feature that will be used quite often, so we should make this delegate method at least (at)optional.

Can you point out some use case where this might be useful?

Cheers,
Alex

[0xMarK]

I'm developing an enterprise application with a complicated user access rights. In few places the app must forbid the user from unchecking some rows while letting editing all other rows. (The user can only see that the row is checked)

I've integrated this modified version to my project and it works great!

Of course this feature isn't needed often. So you are absolutely right, I will make the delegate method optional.

[alexleutgoeb]

Thank you, that looks good, will test this in one of my own apps and merge your pr in master shortly!