const, final, scope function parameters

[Frank Benoit]

> I like this one, basically it's safe by default and saves typing in the most
> common case, it would also avoid the problem I see in c++ sometimes, that
> people don't write const because it's more typing. Walter please
> reconsider, const by default will be worth any initial hassle.

i still second that.
with save default: the compiler will force the user to make the param
mutable if needed.
without save default: it will not complain, when mutable is not needed.