Revision 894868

Moved more non-api (non-dom) classes from the message package (BodyCopier, BodyPart). Separated abstract code from Multipart and moved implementation specifci MultipartImpl to impl package. BodyPart is simply an implementation of Entity. No need to create another level, moved BodyPart to the impl package and changed Multipart abstract class to deal with Entity instead of BodyPart (this is also a bugfix because Message should be "addable" to a Multipart) (MIME4J-156)