String is a class but we treat it as immutable

[marcusnaslund]

This is obviously a big language design choice, but as I see it, we should either

1. make String a cover (would make for easier memory management, but probably break rock completely, and we would be back in Text territory...)

or

2. leave it as a class but modify the methods on String to allow editing an existing String instance instead of creating a new one (easy, since the underlying CharBuffer already does this!). This also simplifies a lot of the memory management code around strings we have today.

(Indeed, this is a big question requiring discussion, and maybe one that will never be fixed.)