This fixes some warnings in 'VectorType vec(size_t)' when VectorType was a
FieldVector< int, ... > bc. of the size_t to int conversion and is a more
general solution in general.

This adds the possibility to convert 'true' and 'false' together with their
uppercase variants to bool. This allows to use an ini file with dune and
python (as it used to be). Fixes #12

This is the more natural situation if some of the norms are actually
estimators. In addition, the EOC should not be affected anyway.

These variable names make reading the error message a bit easier.

Conflicts:
	dune/stuff/test/common_logger.cc

Somehow size_t(...) was 791 while ... was 792, so a std::round(...) might
be better.

Success was previously defined as the results being less or equal to the
expected results, which is not optimal. From now on it is checked whether
the expected result and the result (in scientific notation) are equal in
their first three meaningful digits.