after configure)
- Make CMake module installation path configurable
- Detect CMAKE_MODULE_PATH automatically
  + First call find_package(dune-common) to query its CMAKE_MODULE_PATH
  + Then setup the module path
  + After each find_package of dune module update the CMAK_MODULE_PATH
  + each module exports ist own <package-name>_MODULE_PATH in the
  + package configuration files

[[Imported from SVN: r1714]]

[[Imported from SVN: r1678]]

modul name (lower case with dashes).

These leads to kind of weired variabable names (dune-common_DIR,
dune-common_LIBRARIES, etc.) but finds non-installes modules
easier. You just sets CMAKE_PREFIX_PATH to the directory containing
the modules.

[[Imported from SVN: r1584]]