Add support for nominal (or "named") classes with encapsulation. Inheritance will be in a later proposal. Here is an example of the proposed syntax:
```
class Circle {
fn Create(c: Point, r: f32) -> Self {
return {.center = c, .radius = r};
}
fn Diameter[me: Self]() -> f32 {
return me.radius * 2;
}
fn Expand[addr me: Self*](distance: f32);
private var center: Point;
private var radius: f32;
}
fn Circle.Expand[addr me: Self*](distance: f32) {
me->radius += distance;
}
```
Co-authored-by: Chandler Carruth <chandlerc@gmail.com>