Struct constructors work like built-in type constructors.

[lgritz]

You know how you can have an expression for a built-in type like color?

foo = color(1,1,1)

or

void func (color c) { ...}
func (color(1,1,1);

It was really awkward to do this with structs.

So with this patch, for every struct, you can construct it by name
with a function-call-like syntax, where the arguments must be the same
types as the data members of the struct, in order.

For example:

struct RGBA {
    color rgb;
    float a;
};

RGBA x = RGBA(color(1,1,1), 1);

void func (RGBA x) { ... }
func (RGBA(Cblah,alpha));

You don't need to explicitly declare the constructor like in C++, it
just exists.

[lgritz]

So...

[aconty]

LGTM!