[evol] moved signed/encrypted mail creation from original mail to TMail class, and removed mail object duplication in the process (references to inners objects caused original mail to be altered, copying original headers instead)
[evol] set the 'micalg' parameter in signed mails
[evol] sign outgoing mails, and lot's of fixes and code improvement in mail handling (related to signing, crypting, and preparing/chaining the two)
[evol] handle incoming encrypted messages
[fix] remove logger usage in tmail extension
[evol] properly moved tmail signature handling out of postman in a library (which i should probably suggest upstream)