Added initial implemenation of D2UpdateMgr class to src/bin/d2.

Adds initial implementation of D2QueueMgr class to DHCP_DDNS.
This class is manages the queue of inbound DHCP_DDNS requests.

Changes were largely cosmetic.

Conflicts:
	doc/Doxyfile
	doc/devel/mainpage.dox

The following statement 'buf[i + 1] << 8 + buf[i] & 0xFF' was replaced
with this '(buf[i + 1] << 8) + (buf[i] & 0xFF)' because + operator takes
precedence over << operator.

Applied with trivial whitespace fixes.

If the cmdctl-certfile.pem is older than cmdctl-keyfile.pem for some
reason, make will try to run the rule every time.

DHCP packet pack methods now throw exceptions on error, rather then
returning bool result value.

Removed obsoleted error messages, altered exception by Packet6::packTCP to
be NotImplemented rather than Unexpected.  Corrected method commentary.

These are better replaced with size_ts everywhere, but we set it the
test DomainTree's data, and the data is an int, so it has been changed
everywhere to be an int for consistency.

This is a test that verifies that the tree is balanced, and doesn't go
over the red-black theoretical limit. It constructs a random large
million+ name zone and checks that the distance from every node to its
subtree root is within limit. This is a check that was not implemented
and we should have this as performance correctness proof, as the
DomainTree is so central to our memory datasrc performance.

* Make the code more straightforward to follow
* Add docs to make it easy to understand