in, out and inout for function arguments

[Craig Black]

> When 'inout' is used, it is usually as a compromise to improve 
> performance.
> For example, it can be a performance cost to copy large structs or
> fixed-length arrays betwen functions, and 'inout' is a way to avoid that.

And I think that is gay.  'inout' should not be required to pass an argument 
by reference.
IMO 'in' should pass by reference, but denote a read only parameter.  This 
would be better
for performance and correctness.

-Craig