various tweaks & fixes

Mostly for
https://github.com/libgdx/libgdx/issues/2359
https://github.com/libgdx/libgdx/issues/2524
https://github.com/libgdx/libgdx/issues/2441
https://github.com/libgdx/libgdx/issues/2436

I don't know how I missed that... probably because I stopped searching at writeFields(), and the switch is @ getDefaultValues(). Still, yeah, it's obviously there already, so this one would be totally useless.