Remove explicit code for destructors, and some constructors,
that are automatically defined by modern C++.
Also unpointerize a few objects.

Doxygen & CMake: cleanup, comments, grouping

Hasn't been used since long; didn't cover FFCatalog:
there is little or no advantage in running Latex and
related commands through 'make'.

Doxygen: move instrument description out of group "simulation"

Doxygen: now all variants fully under CMake control

Provide cue why version numbers of Core and of Python module might
disagree.

from Doxygen 1.8.5 to 1.8.17, using "doxygen -u"

should have been done when starting sprint

- Documentation can now be built by command 'make doxyuser'
- configured doxy files now in build/doxygen (no longer under version
  control)
- html output now under html/build

This resolves issue http://apps.jcns.fz-juelich.de/redmine/issues/2385

- rename flag BORNAGAIN_RELEASE -> BORNAGAIN_CONFIGURE_DOXY
- write configured Doxyfiles to auto/Doxygen

CHANGELOG: start new sprint

Release 1.17.0

Release 1.17.0