Optimize matrix assembling in python example
Optimize matrix assembling in python example

ddemidov/amgcl,dondieselkopf/amgcl,huahbo/amgcl,ddemidov/amgcl,ddemidov/amgcl,dondieselkopf/amgcl,huahbo/amgcl,ddemidov/amgcl,dondieselkopf/amgcl,huahbo/amgcl