* .gitignore: Update.

* Makefile.am: Remove SUBDIRS. Make examples build and documentation
build conditional. Build reference documentation with doc-reference.am
from mm-common. Add docs/manual/libxml++.pdf target, but do not enable
it by default. Add autogen.sh and docs/manual/insert_example_code.pl to
dist_noinst_SCRIPTS. Add docs/manual/html/*.html to
MAINTAINERCLEANFILES.

* autogen.sh: Add --enable-maintainer-mode to arguments passed to
configure.

* configure.ac: Add AM_MAINTAINER_MODE. Add a configure argument to
enable the build of the examples. Use mm-common macros to add a
configure argument to enable documentation, and use the glibmm
tagfile. Check for xmllint and db2latex for DTD validation of the
DocBook manual and building the PDF documentation, repectively. Remove
the last non-toplevel Makefiles from AC_CONFIG_FILES.

* docs/Makefile.am:
* docs/Makefile_web.am_fragment:
* docs/manual/Makefile.am:
* docs/reference/Makefile.am: Remove from...