Changed to simpler message.putContent(..) method.
Enforced TYPE field.
Added .getBytes() methods since they are usable when comparing the byte values.
Enforced TYPE filed.
Introduced the type field as required field.
Added the BLANK field since either that or the possibility to create Message objects without a type is needed. This can be used, for example, during decryption and is overwritten once the 'real' message is decrypted.
Adapted to the changes of Message (Type field is now required).
Corrected license header.
Catch a MessagePack exception (MessageTypeException).
Simplified the internal method signatures.