Added a code (for debugging) showing how many integrals an integrator calculated.
Merge branch 'customized_integration' of https://github.com/bempp/bempp into customized_integration
Prevented potential evaluators from allocating too large arrays.
Made the constructor of AccuracyOptionsEx taking vectors work in Python.
Modified the assembler so that the distance between elements -- rather than
clusters -- is used to select the quadrature order.