adapt to the many OPM-material file renames
require opm-core from the opm-material module

this is required to use the exception code of opm-core in
opm-material. Also, the Dune prerequisites of opm-material can be
removed once PR #345 is merged into opm-core...
remove unused variable (quells a warning)
added: we need the dune-common version
fixed: quell deprecation warnings when compiling with DUNE 2.3

file changed location
Merge pull request #71 from akva2/quell_deprecation_warnings

Quell some warnings
Revert "remove unused variable (quells a warning)"

This reverts commit 0feae75ec05a7daca16ba238ac3bbc204b576f7c.
changed: quell warning about unused variable when compiling release builds
Merge pull request #73 from akva2/quell_warnings_attempt_2

Quell warnings attempt 2
Merge pull request #69 from andlaus/adapt_to_new_opm_material_filenames

adapt to the many OPM-material file renames
Extracts the full compiler path and feeds it to cmake.

Previously, specifying the compiler name with a variable
to configure ("configure CC=gcc") lead to CMake complaining
that <builddir>/$CC was not a valid path. This patch fixes
this by extracting the full path with "which <compiler>".
Should fix issue #355.
substituted which with command -v.
Change which test for cmake28 to use command -v.
Test for executable and preserve erroneous path for messages

If an alternate compiler is specified, then check if this is actually
executable before assigning it so that we don't end up with specifying
an empty name to CMake. If the path does not exist, it will be preserved
so that CMake will complain with an easily identifiable error message.
Detect OS version when running on RHEL/CentOS 5.x

These versions only have /etc/redhat-release, not any of the newer
files.
Test variables instead of contents

If you test the contents of a variable, this is not necessarily true
in CMake (since the contents here is a path, and not a variable name;
the default test is "does this variable exist", not "is this a non-
empty string" like in shell script)
Don't set a default search path; use CMake's default

If we set a default search path ourself, then this will be used if we
specify a SuiteSparse_ROOT with error! Instead, we should just leave
our SuiteSparse_SEARCH_PATH variable empty and then let CMake fill in
its defaults. If there is a directory specified on the other hand
(indicating that we want exactly that location), only use that and
turn all the default paths completely off.
Allow use of uppercase version of the _ROOT var

The convention is to use uppercase names, in particular our own
./configure script uses this, so we should at least allow it here
(in addition to the old way for backward compatibility)
Add special variable for MultiArch-unaware components

Some components are not yet MultiArch-aware and installs to either
lib/ (Debian) or lib64/ (RHEL) on 64-bit platforms. If we need to
interface with these components, then it is nice to have such a
variable set together with the regular detection code.
Use MultiArch-unaware path for dune.module

As of 2013-09 the DUNE code that reads dune.module is not MultiArch-
aware. Thus, for a 64-bit platform it will look in lib/ on Debian and
lib64/ on RHEL.