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).
Merge remote-tracking branch 'origin/master' into topic/seth/scripts-for-2.1

Conflicts:
	scripts/base/frameworks/packet-filter/main.bro
Checkpoint on the packet filter framework.

- Packet loss interval changed to 5 minutes by default.  Users
  were getting too many notices from this.

- BPF load balancing (ipv4 and ipv6).  This will tie in with
  upcoming BroControl support for configuring this.

- BPF based connection sampling.

- Small improvements to how and when filters are installed.
Packet filter framework checkpoint.
Several final fixes for PacketFilter framework.

- Fixed how the dpd_* variables are written.

- Fixed a bug with the shunting code.

- Updated a few tests.
Last test update for PacketFilter framework.
Merging master.
Merge remote-tracking branch 'origin/master' into topic/seth/analyzer-framework

Conflicts:
	scripts/base/init-default.bro
	scripts/base/protocols/dns/main.bro
	scripts/base/protocols/ftp/main.bro
	scripts/base/protocols/http/main.bro
	scripts/base/protocols/irc/main.bro
	scripts/base/protocols/smtp/main.bro
	scripts/base/protocols/ssh/main.bro
	scripts/base/protocols/ssl/main.bro
	scripts/base/protocols/syslog/main.bro
	src/main.cc
	testing/btest/Baseline/coverage.default-load-baseline/canonified_loaded_scripts.log
Updates for the PacketFilter framework to simplify it.
Updating test baselines.
Missed a test fix.
Merge remote-tracking branch 'origin/topic/seth/packet-filter-updates'

Closes #1030.

* origin/topic/seth/packet-filter-updates:
  Missed a test fix.
  Updating test baselines.
  Updates for the PacketFilter framework to simplify it.
  Last test update for PacketFilter framework.
  Several final fixes for PacketFilter framework.
  Packet filter framework checkpoint.
  Checkpoint on the packet filter framework.
  Initial rework of packet filter framework.
Bringing back test for enable_auto_protocol_capture_filters (formerly
all_packets).