Fix Phobos dependencies on autodecoding

[Walter Bright]

On 8/16/2019 3:32 AM, Patrick Schluter wrote:
> Unicode is not perfect and indeed the crap with emoji is crap, but Unicode is 
> better than what was used before.

I'm not arguing otherwise.

> And to insist again, Unicode is mostly about "DATA PROCESSING". Sometime it 
> might result to a human readable result, but that is only one part of its purpose.

And that's mission creep, which came later and should not have occurred.

With such mission creep, there will be no end of intractable problems. People 
assign new semantic meanings to characters all the time. Trying to embed that 
into Unicode is beyond impractical.

To repeat an example:

     a + b = c

Why not have special Unicode code points for when letters are used as 
mathematical symbols?

    18004775555

Maybe some special Unicode code points for phone numbers?

How about Social Security digits? Credit card digits?