float init 0 request

[Walter Bright]

Floats are default initialized to NaN so people will be coerced to explicitly 
code what they want the initialized value to be.

I've seen enough code where the programmer forgot to initialize a float, it was 
defaulted to 0, and the wrong result was not detected.

```d
float f;     // code reviewer: did the programmer intend it to be 0?
float g = 0; // code reviewer: yes, the programmer likely meant to initialize it 
to 0
```

It's similar to pointers being default initialized to null. Trying to use a null 
pointer will result in a seg fault.

Most people decry this, but it's actually a great feature. If there's a bug in 
the code, it's better to find it sooner rather than after you ship.