Adding the unified2 analyzer.

- This isn't connected to anything yet.
Merge remote-tracking branch 'origin/master' into topic/seth/metrics-merge
Large update for the SumStats framework.

 - On-demand access to sumstats results through "return from"
   functions named SumStats::request and Sumstats::request_key.
   Both functions are tested in standalone and clustered modes.

 - $name field has returned to SumStats which simplifies cluster
   code and makes the on-demand access stuff possible.

 - Clustered results can only be collected for 1 minute from their
   time of creation now instead of time of last read.

 - Thresholds use doubles instead of counts everywhere now.

 - Calculation dependency resolution occurs at start up time now
   instead of doing it at observation time which provide a minor
   cpu performance improvement.  A new plugin registration mechanism
   was created to support this change.

 - AppStats now has a minimal doc string and is broken into hook-based
   plugins.

 - AppStats and traceroute detection added to local.bro
Merge remote-tracking branch 'origin/master' into topic/seth/sumstats-updates

Conflicts:
	scripts/base/frameworks/sumstats/cluster.bro
	scripts/base/frameworks/sumstats/plugins/average.bro
	scripts/base/frameworks/sumstats/plugins/max.bro
	scripts/base/frameworks/sumstats/plugins/min.bro
	scripts/base/frameworks/sumstats/plugins/sample.bro
	scripts/base/frameworks/sumstats/plugins/std-dev.bro
	scripts/base/frameworks/sumstats/plugins/sum.bro
	scripts/base/frameworks/sumstats/plugins/unique.bro
	scripts/base/frameworks/sumstats/plugins/variance.bro
	scripts/policy/protocols/http/detect-sqli.bro
	testing/btest/scripts/base/frameworks/sumstats/cluster-intermediate-update.bro
Hopefully fixing a strange error.
More adjustments to try and correct SumStats memory use.
SumStats changes to how thresholding works to simplify and reduce memory use.
Fix a reporter message in sumstats.
Add server samples to SSH bruteforce detection.
Rework the DHCP analyzer to make it compatible again.
Tiny fix to account for missing str field  (not sure how this happens yet)
Beginning rework of SumStats API.
Merge remote-tracking branch 'origin/master' into topic/seth/sumstats-updates

Conflicts:
	doc/scripts/DocSourcesList.cmake
	scripts/test-all-policy.bro
Merge branch 'master' into topic/vladg/dhcp
DHCP:

 - Added the known-devices log, and the script to log DHCP hostname per MAC address,
 - Added DPD sig,
 - Removed some scripts following a discussion with Seth.
DHCP: Adding unit tests.
Pluginizing the DNP3 analyzer, plus a basic script logging requests
and replies.

Almost ready, but now 1 test fails again ...

[Note I broke git history by copying over the files into a new branch.]
Updates for SumStats API to deal with high memory stats.

  - The code is a mess and will need to be cleaned up, but the
    tests do pass.
Merge remote-tracking branch 'origin/master' into topic/seth/sumstats-updates
Fix the SumStats top-k plugin and test.