Add a name above head line rendering API

[Yedelo]

Make a NameLineAPI, HeadLineAPI, whatever, an API for rendering lines above a players's head.
This would be driven by, for consistency, a NameLineEvent. This would expose a list of NameLines, which could be modified with NameLineBuilders.
Example code:

@Subscribe
public void addSimpleNameLine(NameLineEvent event) {
    event.getNameLines().add(new NameLine().setText("Hello").showWhileSneaking(true));
}

Current consumers of this event would be strength indicatora and bounty hunting, and it could allow for easier displaying of information.