check for the C++-2011 'auto' keyword.

It seems like the corresponding FindCXX11Features.cmake file
was not updated for this module.
make the c++-2011 feature set of GCC 4.4 mandatory

we now produce an error even if the module in question does not
actually use some of these features.
replace Dune and boost classes by their C++-2011 equivalents

that is, provided that they are available in GCC 4.4. This basically boils
down to Dune::array and boost::array.
Merge pull request #38 from andlaus/gcc-4.4

Gcc 4.4