Add method to rotate a relative location around a location in the world.

Use method for entity follow, still requires some tweaks and additions.

On line 67 do you want for example only the yaw to be used if hologram.isRelativePitch() is false and vice versa?
Also not sure what isRelativePitchControlMoreThanHeight is supposed to do so I just added some temp code in there.

Here is the plugin I used to test it:
```Java
    @Override
    public void onEnable() {
        getServer().getPluginManager().registerEvents(this, this);
    }

    @EventHandler
    public void onJoin(PlayerJoinEvent event) {
        // X = Right(Neg) - Left(Pos)
        // Y = Up(Pos) - Down(Neg)
        // Z = Behind entity(Neg) - In front entity(Pos).
        new Hologram(event.getPlayer().getEyeLocation()
                .add(0, 0, 6), ChatColor.GOLD + "This is a hologram",
                ChatColor.RED + "Center").setFollowEntity(event.getPlayer(), false, true, true, false)
                .start();

        new Hologram(event.getPlayer().getEyeLocation()
                .add(0, 2, 6), ChatColor.GOLD + "Top").setFollowEntity(event.getPlayer(), false, true, true, false)
                .start();

        new Hologram(event.getPlayer().getEyeLocation()
                .add(0, -2, 6), ChatColor.GOLD + "Bottom").setFollowEntity(event.getPlayer(), false, true, true, false)
                .start();

        new Hologram(event.getPlayer().getEyeLocation()
                .add(-3, 0, 6), ChatColor.GOLD + "Right").setFollowEntity(event.getPlayer(), false, true, true, false)
                .start();

        new Hologram(event.getPlayer().getEyeLocation()
                .add(3, 0, 6), ChatColor.GOLD + "Left").setFollowEntity(event.getPlayer(), false, true, true, false)
                .start();
    }
```
I'm sorry, this math is just wat. I don't even understand it.
https://github.com/md-5/SmallPlugins/blob/master/TestPlugin/src/main/java/net/md_5/TestPlugin.java

That is the correct and simple way of doing this.