* Essentially copy and adapt the definition of AC_CHECK_LIB.  This should
   make sure the two macros behave the same even in corner cases (except for
   the added functionality, of course).

 * Properly document what exactly is allowed in the arguments.

Parse arguments to DUNE_CHECK_LIBS_EXT properly in parmetis.  This avoids
expansions like 'LDFLAGS="$LDFLAGS -L"$PARMETISLIBPATH""'.

[[Imported from SVN: r5830]]

[[Imported from SVN: r5818]]

 * Adapt superlu-dist.m4, parmetis.m4, hdf5.m4, dune/common/test/Makefile.am
   and duneproject to the MPI changes.

 * Add DUNE_CHECK_LIB_EXT, a wrapper around AC_CHECK_LIB which allows to set
   the library path.

[[Imported from SVN: r5814]]

[[Imported from SVN: r5756]]

[[Imported from SVN: r5583]]

Removed default include path.

[[Imported from SVN: r5577]]

[[Imported from SVN: r5574]]

Fixed parmetis check. Parmetis is only enanbled if the correct
CPPFLAGS are used (just like MPI).

[[Imported from SVN: r5573]]

[[Imported from SVN: r5259]]

  modules
  * add support for suggests
  

[[Imported from SVN: r5156]]

[[Imported from SVN: r4550]]

[[Imported from SVN: r3821]]

[[Imported from SVN: r3437]]

[[Imported from SVN: r3436]]

/usr/include. Parmetis is now found without path.

[[Imported from SVN: r3347]]

[[Imported from SVN: r3168]]

[[Imported from SVN: r2424]]

[[Imported from SVN: r1938]]

values of MPI.

[[Imported from SVN: r1915]]

[[Imported from SVN: r1913]]