Fix awesome MjBattery thing for Scala

Since Scala compiler makes all fields private and creates getters and setters for them, i check, if there is a public(so private Scala fields doesn't count) Scala setter and if is, then set proper accessibility for the field.
You can also find some info about that in comments in cpw.mods.fml.common.ILanguageAdapter.ScalaAdapter class.

Tested.