use phase pressure to compute FVF.
Add DuneMatrix class.

This is a hack to get a more efficient constructor for dune-istl
matrices from Eigen matrices.
Compile fix for Dune 2.2.

Some BCRSMatrix members are new in 2.3.
Remove unused code.
Obtain dune-istl version for config.h.

Required by DuneMatrix.hpp.
Merge pull request #208 from qilicun/fvf_phase_pressure

use phase pressure to compute FVF.
Fix usage of result from computePressures().
Remove unneeded template argument.
Merge pull request #214 from atgeirr/fix-pressure-usage

Fix usage of result from computePressures().
Merge pull request #210 from atgeirr/dune-matrix-hack

Add a horrible hack: DuneMatrix class.
Don't use 'typename' in non-template context

This fixes the build on GCC 4.4.

Pointy hat: @bska
Merge pull request #215 from bska/fix-build-gcc44

Don't use 'typename' in non-template context