[[Imported from SVN: r6063]]

  - Introduce autoconf substitutions DUNEMPICPPFLAGS, DUNEMPILDFLAGS and
    DUNEMPILIBS.
  - Deprecate MPI_LDFLAGS and MPI_CPPFLAGS: the automake manual recommends
    against "_" in names of such variables, MPI_LDFLAGS actually contains
    mainly libraries and simply changing MPI_LDFLAGS to MPI_LIBS will probably
    break a lot of stuff.  By deprecating MPI_CPPFLAGS it is possible to make
    the preprocessor generate a deprecation warning with instructions to
    change both MPI_CPPFLAGS and MPI_LDFLAGS (though this has yet to be
    implemented).

[[Imported from SVN: r5806]]

[[Imported from SVN: r5756]]

[[Imported from SVN: r5177]]

[[Imported from SVN: r4936]]

[[Imported from SVN: r4884]]

[[Imported from SVN: r4882]]

[[Imported from SVN: r4735]]

* added support for environment variables $MAKE and $GREP to dunecontrol
* updated buildsystemhowto

[[Imported from SVN: r4721]]

[[Imported from SVN: r4717]]

[[Imported from SVN: r4715]]

[[Imported from SVN: r4698]]

Wrote a small shell function to find the canonical path of the shell
programs.

[[Imported from SVN: r4697]]

[[Imported from SVN: r4623]]

MPI. This might be useful for those people who wnat to compile alugrid with
MPI and want to easily switch the compiler.

[[Imported from SVN: r4620]]