A few improvements to SortedRange

[Andrei Alexandrescu]

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.

https://github.com/D-Programming-Language/phobos/commit/b6aabf2044001ea61af15834dcec5855680cf209

http://d-programming-language.org/cutting-edge/phobos/std_range.html#SearchPolicy

http://d-programming-language.org/cutting-edge/phobos/std_range.html#SortedRange


Andrei