This allows tincctl to receive log messages from a running tincd,
independent of what is logged to syslog or to file. Tincctl can receive
debug messages with an arbitrary level.
Scripts called by tinc would inherit its open filedescriptors. This could
be a problem if other long-running daemons are started from those scripts,
if those daemons would not close all filedescriptors before going into the
background.
Problem found and solution suggested by Nick Hibma.
Apart from the platform specific tun/tap driver, link with the dummy and
raw_socket devices, and optionally with support for UML and VDE devices.
At runtime, the DeviceType option can be used to select which driver to
use.
