Support for (mixed) MPLS and VLAN traffic, and a new default BPF

filter. (Seth Hall and Robin Sommer)

- Merging in the patch from #264, which provides support for mixed
  VLAN and MPLS traffic.

- Changing Bro's default filter from being built dynamically to being
  a static "ip or not ip". To get the old behaviour back (i.e., the
  dynamically built filter), redef "all_packets" to false.

- print-filter.bro now always prints the filter that Bro is actually
  using, even if overriden from the command line.

src/Net.h

@@ -58,9 +58,6 @@ extern int have_pending_timers;
 // is the speedup (1 = real-time, 0.5 = half real-time, etc.).
 extern double pseudo_realtime;
 
-// Pcap filter supplied by the user on the command line (if any).
-extern char* user_pcap_filter;
-
 // When we started processing the current packet and corresponding event
 // queue.
 extern double processing_start_time;