This enables users to have several build directories like
build-clang, build-gcc5, build-debug, and still get all
of them ignored.

This includes the following workflow:

* The cmake module path is globbed for any modules matching *.cmake
* The opening comment is parsed for the following rst directives:
  cmake_function, cmake_module, cmake_variables
* From those, a browsable documentation is generated.

To run properly, a python interpreter and sphinx are needed.

Add missing files, remove ancient buildsystem stuff and stuff where it is
unclear where it comes from.

"Makefile.in", "*.o", etc. need only be listed in the toplevel .gitignore, the
rules are applied recursively.

Test programs etc. should be listed as "/program" in their directory's
.gitignore, so they are not accidentially ignored in a lower level directory.

[Bugfix] Prevent definition of HAVE_BOOST without value due to race conditions in some autoconf versions.

For some autoconf versions there was a race condition between ax_boost_base.m4 and dune_boost_base.m4 resulting in HAVE_BOOST being defined with no value (instead of ENABLE_BOOST). For others there were even two definitions of it (one with and one without value). 

This patch renames the symbol being defined in dune_boost_base.m4 to HAVE_DUNE_BOOST and defines a value for it if boost is found.

Please change your code such the preprocessor directives checking for boost from
#if HAVE_BOOST
to
#if HAVE_DUNE_BOOST

Resolves flyspray 1265 and presumably 1249.

[[Imported from SVN: r7422]]

[[Imported from SVN: r7361]]

[[Imported from SVN: r7122]]

[[Imported from SVN: r5756]]

[[Imported from SVN: r5648]]

[[Imported from SVN: r5214]]

[[Imported from SVN: r4761]]

[[Imported from SVN: r4596]]

[[Imported from SVN: r4559]]

[[Imported from SVN: r4500]]

[[Imported from SVN: r1828]]

tested on autotool-agnostic systems

[[Imported from SVN: r1241]]

[[Imported from SVN: r1191]]

[[Imported from SVN: r991]]

[[Imported from SVN: r852]]

[[Imported from SVN: r252]]

  can be installed into a system
- wrote m4-macros so that any program using dune can check for
  albert/ug/dune them self

[[Imported from SVN: r79]]

[[Imported from SVN: r1]]