Sokol now has official D bindings

[ryuukk_]

It'll be interesting to know what the experience was for the 
maintainer to play around with D (for the first time?)

 From what i could gather, problems encountered:

- rvalue ref params (wich led to someone telling him to use 
-preview=all wich led to other issues)

- attributes soup

- float nan default

- no warning on use of uninitialized floats


I think it is time to decide what to do with all these -previews, 
rvalue ref params should be a feature already imo

For float nan default, i personally think everything should be 
consistent therefore 0 initialized