daemon: Ignore time-sync replys with insufficient rating
ibrcommon: MonotonicClock class added
ibrdtn: Add global monotonic clock to Clock class
ibrdtn: Replaced code of getUptime() with MonotonicClock
daemon: Generate TimeEvent TICK with MonotonicClock
daemon: Use MonotonicClock to manage blacklist in DT-NTP mechanism
daemon: Use MonotonicClock to block unnecessary handshake queries
daemon: Use MonotonicClock instead of unix timestamp in prophet routing
Monotonic clock support

This merge adds monotonic clock class to ibrcommon and changes
some mechanism to use it instead of global timestamps. With
this change these mechanisms should safe against jumping clock
values.