[trac871] Revert "[trac871] implemented a minimal set of python lib for TSIG: just allowing construction of TSIGContext and add another signature to Message.to_wire() to send a signed message."

(this was committed to the wrong branch)

This reverts commit d6db622c.

[trac871] implemented a minimal set of python lib for TSIG: just allowing construction of TSIGContext and add another signature to Message.to_wire() to send a signed message.

Conflicts:
	src/lib/dns/tsig.cc

Conflicts:
	doc/Doxyfile
	src/lib/Makefile.am
	src/lib/cryptolink/cryptolink.cc
	src/lib/dns/tsigkey.cc
	src/lib/util/unittests/Makefile.am
Other fixes:
 - cppcheck filter adjustment
 - (indirect) dependency on libbotan.  actually we should be able to make
   the link within libcryptolink, so I chose that approach.  hopefully
   it doesn't break autobuild.

they were actually not "SOURCES", and caused distcheck failures.
discussed on jabber.

use -L`botan-config --prefix`/lib and -I`botan-config --prefix`/include.

if nothing (or --with-botan) is specified it will be taken from $PATH, if --with-botan=dir is specified it will be taken from $withval/bin
If --without-botan is specified configure will print an error

they use AbstractMessageRenderer.
not related to the subject of this branch, but we'll need this change anyway,
and touching some toWire()s is a good opportunity to make this happen.

also made the return value of toWire() compatible with its RRset variants,
and added truncation case consideration.

not directly related to the main purpose of this branch, but this is
a deferred cleanup from the initial step of this task.

[trac812next] implemented TSIG signing main part: add TSIGRecord::toWire() and have the Message class use it with a TSIGContext.
(There are some other small cleanups in this commit)

not directly related to the main subject for this branch, but we need
this fix to make the main code work correctly.

(also made a minor editorial cleanup: removed a redundant space in .cc)

likely to be getting bigger.

consists of the originally proposed patch with additional fixes to bin/stats
to make it testable

Conflicts:
	configure.ac
	doc/Doxyfile
	src/lib/Makefile.am

Also updated includes (because of the lib/util move)

added new test for that.
with some other cleanups.