In the process:
* change upstream to https://github.com/juha-h/libzrtp
* remove patches that are already integrated by upstream
* avoid hidden dependency on doxygen
Zfone is VoIP encryption software, designed by Phil Zimmermann of PGP. This
SDK is suitable for inclusion in software VoIP clients, firmware for hardware
VoIP phones, VoIP PBX servers, mobile VoIP clients, and SIP border control
servers. The SDK enables interoperation with the rest of the ZRTP community.