Allow packages to add source code to the project

By returning a ${package}_SOURCES variable with the names of the code,
it will be propagated to ${project}_SOURCES and subsequently compiled
into the library.

AGMG (Algebraic Multigrid) uses this functionality.
Make opm-core pick up AGMG through the standard list
Don't add AGMG in an ad-hoc way

Use the standard prerequisite list instead.
Use system-provided MUMPS library for AGMG

This require us to compile in a small glue module which maps the
name of the internal routine to the system routine.
Enable use of parallel version of MUMPS

If we have enabled MPI, then we must call MPI_Init and MPI_Finalize
in the program anyway so we may as well use the parallel version of
MUMPS.
Use parallel version if and only if MPI is installed
Function has a different name in the parallel vs. serial version
detect the presence of std::shared_ptr

since GCC 4.4 supports it, make it mandatory as well...
use std::shared_ptr instead of boost::shared_ptr

our policy is that we only use boost if necessary, i.e., if the oldest
supported compiler does not support a given feature but boost
does. since we recently switched to GCC 4.4 or newer, std::shared_ptr
is available unconditionally.
add a few config.h macros useful for dune-common
also test for std::unique_ptr
replace boost::scoped_ptr by std::unique_ptr

thanks to Bård Skaflestad, Atgeirr Rasmusen and Roland Kaufmann for
the hint.
OPM Porsol now depends on OPM Material

In the new build scheme, the prerequisites of each module is declared
in this file as the canonical version, and everything else includes it.
Merge pull request #316 from rolk/316_material

OPM Porsol now depends on OPM Material
Merge pull request #313 from andlaus/use_std_shared_ptr

Use std shared ptr
add and use CMake modules for valgrind client requests and quadruple precision math
add test for <type_traits> to FindCXX11Features.cmake

I fogot this one yesterday...
add a cmake check for the abi::__cxa_demangle() function

this was also forgotten. sorry...
make the build system link to the "quadmath" library if it is supported

Thanks a lot to Roland Kaufmann for the support.
Merge pull request #315 from andlaus/checks_for_quadmath_and_valgrind

add and use CMake modules for valgrind client requests and quadruple precision math