• Add asterisk 16.0.0 to ports
• Update g72x module to 1.4.3, which add support for asterisk 16
• Add asterisk16 flavor and conflicts to asterisk modules ports which support it
• Add conflicts to other asterisk versions ports
• Add deprecation notice to asterisk15 which will reach EOL on 2019-10-03
• Fix wording on SOUNDS option description
• Remove old MOVED line for asterisk16 which was for the long removed asterisk 1.6 version

Approved by: portmgr (flavors already approved in the past)