Ranges of char and wchar

[Walter Bright via Digitalmars-d]

On 5/8/2014 10:46 AM, Andrei Alexandrescu wrote:
> A discussion is building around
> https://github.com/D-Programming-Language/phobos/pull/2149, which is a nice
> initiative by Walter to allow Phobos users to avoid or control memory allocation.

The setExtension() function is itself not very important, but what is important 
is an example for how to put together ranges.

Some design goals:

1. purity, @safe, nothrow, @nogc
2. composability
3. have them work in a consistent way, so there's less for a user to learn