Unit multiplication

[Marcus-Sie]

I would request to add Unit * Unit multiplication and devison.
At the Moment only Unit * double is implementet

// Summary: // Multiplies a Unit with a double. public static Unit operator *(Unit l, double r); // // Summary: // Multiplies a Unit? with a double. public static Unit? operator *(Unit? l, double r); // // Summary: // Divides a Unit by a double. public static Unit operator /(Unit l, double r); // // Summary: // Divides a Unit? by a double. public static Unit? operator /(Unit? l, double r);