single-arg registerClass() method now throws an exception
if the object is not marked Serializable. Internally,
the package-load stuff uses the new alternate method that
allows safe non-exception throwing registration since it's
hitting it with every class in a package.
Interestingly enough, messages will still get written out
because of some questionable code in writeClassAndObject()...
but it won't be read as anything but null despite its
40+ bytes of data.
git-svn-id: https://jmonkeyengine.googlecode.com/svn/trunk@7121 75d07b2b-3a1a-0410-a2c5-0572b91ccdca
99a21a8c1d