updated S_ChatMessage
minor fix
Merge branch 'master' into elias
S_ChatMessages are now Serializeable
added Envelope class
now Serializable
added S_Content class
now supports MAC-verification
extended new structure of the Crypto partition
simplified structure and extended affected classes
Merge branch 'master' into elias

Conflicts:
	src/com/crypto/S_ChatMessage.java
symmetric message encryption and MAC-verification now working
now easier message encryption with EnvelopeFactory
message structure change
SecureMessage now using the new message structure
message structure now generic
slight updates in the structure and removed unnecessary classes
Merge pull request #22 from gye-tgm/elias

Elias