[FR] Allow daisy-chaining when adding children to ValueTrees

It turns out that returning the child ValueTree isn’t as safe as it first seems.

If you did something like this…

    auto child = juce::ValueTree("parent")
        .addAndReturnChild(juce::ValueTree("child"), nullptr);

…the “parent” ValueTree would go out of scope, and you’d be left with an orphaned child. The existing API forces us to keep “parent” in scope, thus avoiding this problem.

See my other post here: