Modularise msgbase

Modularise msgbase
  - offer to not call the msg hooks (and set the preivous default in all places)
  - move the serialization of messages into own functions
  - split saving of messages and saving of new messages and make them use each other
Fix import / export
  - don't use fingercount strlen(), CPP can do that way better.
  - properly de-serialize messages so we know they're good.
  - don't roll our own message saving facilities, use the common one (which then also does the big message data splitting)