b10-dhcp-ddns now checks for NXRRSET on DNS removal, rather than NXDOMAIN

Also moved entry 767 above the beta release line.

Python data.merge function now does "deep" merges

The merge logic was simplified a bit and the commentary was improved.

 - GenericLeaseMgrTest class moved to a separate file
 - @todo added for disabled tests in memfile (with explanations)
 - Added several comments

Also, a couple of trivial changes, mostly documentary.

The merge function defined in isc.cc.data module did not correctly
do deep merges, so map sub elements were simply be replaced rather
than merged.

Changed NameRemoveTransaction to test for NXRRSET not NXDOMAIN.  Since
the remove prequisites are RRSet tests, if the RRSets do no exist the
DNS server will return NXRRSET. NameRemoveTransaction now correctly
checks for this and treats it as success.

Got rid of nodistdir and used noinst_ instead of nodist_
for dhcp hooks tests

Also use -rpath /nowhere as a hack to trigger libtool to not create a
convenience archive, resulting in shared modules.

The distcheck builders are unavailable due to vmware issues.
wlodek noticed missing distfiles in my generated tarball when
he tried to do a gtest build.

I verified the patch.
Patch okayed by TomM on jabber.

for a Backward incompatible or operational change.

It previously looked like a command name.
suggested via jabber

This was noticed when trying to do distcheck build on non-Linux.
(Our non-Linux automated builder disappeared.)
I tested this and okayed by muks on jabber.

okayed by muks on jabber

using reorder_message_file.py tool

reduce long lines and
use a tab before the keyword type.
use two tabs before the committer username.