Improve the quadrature rule test

Summary

This MR fixes several shortcomings in the quadrature test. It changes all double to ctype in test-quadrature and use ADL for the lookup of abs and pow to allow other than standard floating point types to be used in quadrature rules. The test is extended to Float128 type.

Details

In the previous implementation of the test-quadrature.hh and in the quadrature rules were some problems:

• In several places explicit use of double
• qualified names for std::abs and std::pow
• Specialization for 1d rules to be constructed from string if numeric_limits<ctype>::is_specialized. This is is probably to correct, since, e.g., Dune::Float128 is specialized but should be constructed from string instead of from double
• Dune::GMPField does not work in the current implementation (I have not found the reason why)
• The test fails if LAPACK is not enabled

These problems are cleaned up:

• Use ctype everywhere and provide replacement for numeric_limits<ctype>::epsilon if not available.
• Prefer using std::abs; using std::pow over qualified names
• Specialization for 1d rules is done with std::is_floating_point<ctype>::value. This should be correct, since in this specialization the numbers are constructed from floating-point numbers in double format.
• GMPField is not fixed, but Float128 is tested instead.
• The GaussJacobi_n_0 test is disabled in case LAPACK is not found.

Closes #24 (closed)