Merge pull request #211 from endJunction/WeightedSumGaussLegendre

[MaL] Replace Gauss-Legendre algorithm with compile-time implementation.
Merge branch 'master' into RegularShapeGaussQuadr

For compile-time GaussLegendre integration algorithm.
[MaL] Move GaussLegendre coeff. definitions in cpp.

Also remove repetitive order definitions.
[NL] IntegrateGaussRegular: Add assert on index and integration order.
[NL] Update for compile-time GaussLegendre integration.