std.parallelism: Final review

[Lars T. Kyllingstad]

David Simcha has made a proposal for an std.parallelism module to be 
included in Phobos.  We now begin the formal review process.

The code repository and documentation can be found here:

  https://github.com/dsimcha/std.parallelism/wiki
  http://cis.jhu.edu/~dsimcha/d/phobos/std_parallelism.html

Please review the code and the API, and post comments in this thread 
within the next three weeks.

On 25 March I will start a new thread for voting over the inclusion of 
the module.  Voting will last one week, until 1 April.  Votes cast before 
or after this will not be counted.

David, do you have any comments?

-Lars