std.datetime is too big

[Steve Teale]

> Thank you for your comprehensive response. It's very appreciated. I am
> also interested in knowing why splitting the module was dropped. As I
> said, it would make things a bit clearer, especially since the sources
> embark the unit tests.
> And a Ddoc page that spans a hundred screens long strikes me as unsound.
> 
We should however thank Jonathan for the work he put into the 
documentation. It may be long, but it is thorough. Would you rather have 
the documentation from std.socket?

Steve