A few improvements to SortedRange

[bearophile]

Andrei:

> I just committed a few improvements to phobos' SortedRange, notably 
> adding various search policies and improving the existing routines. 
> These changes will be rolled out in the next dmd release. Until then, 
> feel free to suggest any improvements.

That SearchPolicy will be enough for maniacs too (it just lacks optional galloping sound effects), very good Andrei :-)

Bye,
bearophile