Import improvement

[Kapps]

I like the idea of being able to either import a module, or 
package, with being able to choose what you want to import from 
it.

Something like
import std.stdio : writeln; (already exists)
import std : stdio, algorithm;
or just 'import std', though for something like std that would of 
course not be recommended. For smaller packages, such as 
std.datetime though, it would be useful.