DIPX: Enum Literals / Implicit Selector Expression

[ryuukk_]

Just right now i got annoyed with enums again while porting an 
old library


![screenshot](https://i.imgur.com/opXDWh5.png)

```D
ctx.allocator.create!(JSONValue)(JSONValue.ValueType.NULL)
```

vs

```D
ctx.allocator.create!(JSONValue)(.NULL)
ctx.allocator.create!(JSONValue)(#NULL)
ctx.allocator.create!(JSONValue)(_.NULL)
```


Unnecessary repetitions and verbosity in my opinion

I could put the with() next to the switch, but still, it's moving 
the problem