Upgrade net/axa to version 2.0.1:

• Update support of libedit <= 3.11 (forced wchar support)
• Deprecate use of self-signed certs
• Add SIGINFO (ctrl-t) information getter for sratunnel/radtunnel
• Add tools option to disable output buffering
• Remove mgmt
• Add stats (successor to mgmt)
• Add library versioning
• Add client-side hello allowing client to send system and dependency information
• Update various internal AXA protocol semantics for AXA Protocol 2
• Add 8601 timestamps to accounting messages

Sponsored by: Farsight Security, Inc.