bugfix NativeJavaClass class.

currently, we can construct java object.
fixbug NativeRegExp is implements Constructor
deprecate Kit.codeBug()

add RhinoRuntimeError
replaced the Kit.codeBug() to proper exception
AST API no changed
improved MessageProvider

There is no need for native2ascii tool anymore. It is sufficient to use
the UTF-8 encoding properties file.
add japanese message resource.