Vibe.d diet templates

[Steven Schveighoffer]

On 6/17/21 12:26 PM, JG wrote:

> Thanks, this works. I would have thought this would be a common enough 
> use case to have support in diet. Anyone else wanted this?

I haven't found a need for it, as I'm usually only dynamically 
configuring attribute values, not attribute names. But my web-fu is 
pretty weak.

However, what I *have* wanted is to have attribute values support 
`Nullable!T` such that they are only included if the item is non-null. 
See [here](https://github.com/rejectedsoftware/diet-ng/issues/28).

-Steve