Improve usability by adding two convenience libraries

[atmoos]

Currently, if I want to create say one meter, I always need to write: Length.Of(1, Si<Metre>()).

This is semantically clean but a tad verbose. Hence create two convenience libraries

• Atmoos.Quantities.Convenience
• Atmoos.Quantities.Units.Convenience

that would expose types that'd enable the following syntax:

Length oneMetre = 1 * m;

Velocity oneKpH = 1 * km/h;

// similary,
var oneSecond = 1 * s;
var threeOhm = 3 * Ω;