Add Javadoc for factory classes.

git-svn-id: http://kryo.googlecode.com/svn/trunk@402 a9660ef0-a895-11de-8ba5-91705c1537ed
Add a missing Kryo constructor for compatibility with previous Kryo versions. This constructor got accidentally removed during recent re-factorings. 

git-svn-id: http://kryo.googlecode.com/svn/trunk@403 a9660ef0-a895-11de-8ba5-91705c1537ed
Fix issue #99: Add void as a legitimate primitive type. Now it is possible to do kryo.writeObject(output, void.class) and kryo.writeObject(output, Void.class).

git-svn-id: http://kryo.googlecode.com/svn/trunk@404 a9660ef0-a895-11de-8ba5-91705c1537ed