Initial rework of packet filter framework.

- Large rework on packet filter framework to make many things easier.
   - Removed the PacketFilter::all_packets variable because it was confusing.
   - New variable (PacketFilter::enable_auto_protocol_capture_filters) to re-enable the old filtering model of only sniffing ports for analyzed protocols.
   - In progress plugin model for adding filtering mechanisms.
   - New default single item for capture_filters = { ["default"] = PacketFilter::default_capture_filter };
   - Mechanism and helper functions to "shunt" traffic with filters.

- Created the Protocols framework to assist with reworking how base protocol scripts are registered with DPD and other things.
   - Protocols framework creates BPF filters for registered analyzers. (if using PacketFilter framework in that mode).

scripts/base/protocols/smtp/main.bro

@@ -1,4 +1,5 @@
 @load base/frameworks/notice
+@load base/frameworks/protocols
 @load base/utils/addrs
 @load base/utils/directions-and-hosts
 
@@ -66,11 +67,9 @@ redef record connection += {
 	smtp_state: State &optional;
 };
 
-# Configure DPD
-redef capture_filters += { ["smtp"] = "tcp port 25 or tcp port 587" };
-redef dpd_config += { [ANALYZER_SMTP] = [$ports = ports] };
-
-redef likely_server_ports += { 25/tcp, 587/tcp };
+global analyzers = { ANALYZER_SMTP };
+redef Protocols::analyzer_map["SMTP"] = analyzers;
+redef Protocols::common_ports["SMTP"] = ports;
 
 event bro_init() &priority=5
 	{