First Draft: ref For Variable Declarations

[Walter Bright]

Sure, they're all different.

 > in C#, to pass by reference, you have to put ref also before the argument in 
the function call

That makes refactoring much more work. By putting ref at the function 
declaration, you can switch it on and off without having to change anything else.

C++ can have refs to null:

```
int *p = NULL;
int& r = *p;
```

You're not supposed to do that, but compilers don't detect it.

As for Zig, in D a ref is a single element pointer, a [] is a pointer to an array.

A special pointer to a 0 terminated array does not confer any useful semantics I 
can think of - one could do it in D by just making the pointer a field in a 
struct and overload the operators.

Essentially, we're in good shape here.