Parsing into compile-time known data structures

[anarthal]

Expose a native API that allows users to parse rows directly into custom, compile-time data structures. E.g.

std::tuple<T1, T2, T3> tuple_row;
resultset.read_one(tuple_row)

struct X
{
    T1 m1;
    T2 m2;
};

BOOST_DESCRIBE_STRUCT(X, (), (m1, m2))

X struct_row;
resultset.read_one(struct_row)