Adding PPPoE support to Bro.

- Still needs a small test tracefile and test.
Add tests of the Bro scripting language

Added tests of all built-in Bro data types (including different
representations of constant values, and max./min. values), keywords, and
operators (including special properties of certain operators, such as
short-circuit evaluation and associativity).
Add more language tests

Added tests for the conditional operator, operator precedence,
modules ("module" and "export" keywords, and the "::" operator), and
for the "copy" keyword.

Also improved tests of max/min values of int, count, and double constants.
Merge remote-tracking branch 'origin/master' into topic/dnthayer/language-tests
Update language tests

Updated the int and count max/min constant value tests based on latest fixes
in master.
Add more language tests

Added more tests and fixed a broken test.
Add more language tests
Add more language tests
Update language tests for recent bug fixes
Merge remote-tracking branch 'origin/master' into topic/dnthayer/language-tests
Add an item to FAQ page about broctl options
reorder a few statements in scan.l to make 1.5msecs etc work.

Adresses #872
Small change to non-blocking DNS initialization.

The trailing dot on "localhost." circumvents use of /etc/hosts in
some environments (I saw it on FreeBSD 9.0-RELEASE-p3) and so emits
an actual DNS query.  When running the test suite, that would be
hundreds of useless queries.
Adjusting some unit tests that do cluster communication.

Added explicit synchronization and termination points to make the
tests more reliable and exit earlier in most cases.
Unit test reliability adjustment.

Sometimes manager node was shutting everything down before others had
a chance to generate output.  It now waits for all nodes to fully
connect with each other.
Adjusting Mac binary packaging script.

Setting CMAKE_PREFIX_PATH helps link against standard system libs
instead of ones that come from other package manager (e.g. MacPorts).

Changed to allow only more recent CMake versions to create packages
due to poorer clang compiler support in older versions, important
since clang is now the default compiler instead of gcc on Macs.
Update compile/dependency docs for OS X.
Fix construction of ip6_ah (Authentication Header) record values.

Authentication Headers with a Payload Len field set to zero would cause
a crash due to invalid memory allocation because the previous code
assumed Payload Len would always be great enough to contain all
mandatory fields of the header.  This changes it so the length of
the header is explicitly checked before attempting to extract fields
located past the minimum length (8 bytes) of an Authentication Header.

Crashes due to this are only possible when handling script-layer events
ipv6_ext_headers, new_packet, esp_packet, or teredo_*.  Or also when
implementing one of the discarder_check_* family of functions.
Otherwise, Bro correctly parses past such a header.
Merge remote-tracking branch 'origin/fastpath'

* origin/fastpath:
  Fix construction of ip6_ah (Authentication Header) record values.
  Update compile/dependency docs for OS X.
  Adjusting Mac binary packaging script.
  Unit test reliability adjustment.
  Adjusting some unit tests that do cluster communication.
  Small change to non-blocking DNS initialization.
  reorder a few statements in scan.l to make 1.5msecs etc work.
Merge remote-tracking branch 'origin/topic/dnthayer/language-tests'

* origin/topic/dnthayer/language-tests:
  Update language tests for recent bug fixes
  Add more language tests
  Add more language tests
  Add more language tests
  Update language tests
  Add more language tests
  Add tests of the Bro scripting language