AM_PROG_MKDIR_P is deprecated; see `Obsolete Macros' in the automake manual

Kudos to Elias Pipping

[[Imported from SVN: r7029]]

for older automake versions

: merge to release

[[Imported from SVN: r5892]]

[[Imported from SVN: r5815]]

* make distcheck work
* make out-of-source builds for tarballs work
... all this only for dune-common...

[[Imported from SVN: r5811]]

[[Imported from SVN: r5804]]

[[Imported from SVN: r5797]]

- add proper web-install target that seperated recursion and local targets
- move web-install to documentation, so that you can call "make web.install" from top-src
- provide fallback targets, if doxygen and/or wml is missing

[[Imported from SVN: r5792]]

[[Imported from SVN: r5784]]