add a template class of Gauss quadrature for regular shape elements, i.e. line, quad and hex
add TestFemIntegration
[IntegrationGaussRegular] getPoint() -> getWeightedPoint()

Changed also the return type from std::tuple to std::array.
Using TemplateWeightedPoint in class IntegrationGaussRegular.
[NL] small improvements in gauss regular integration.
Merge branch 'WeightedSumGaussLegendre' into RegularShapeGaussQuadr
Update for compile-time Gauss integration.