Add format future to Phobos date time

[Kagamin via Digitalmars-d]

On Friday, 11 November 2016 at 06:01:49 UTC, Vladimir Panteleev 
wrote:
> https://github.com/CyberShadow/ae/tree/master/utils/time

BTW what 'C' format specifier means? 
https://github.com/CyberShadow/ae/blob/master/utils/time/format.d#L65 I noticed dfeed uses it too and formatted time stings end with this mysterious 'C'.