Fyrd

This version represents a large API break and a significant step towards making fyrd more similar to the multiprocessing library.

The largest change in this version is that way the Job objects return outputs. Previously, Job.get() would return (exitcode, stdout, stderr), now it just returns the output, which is either the function return value, or the contents of STDOUT.

In addition, now all other variables (.out, .stdout, .stderr, and .exitcode) are saved automatically and the temp files cleaned up by default after get() completes.

The one potential downside is that very large return values get loaded into memory by default. That can be avoided by using wait() instead of get().

Specific changes:

• Make file cleanup the default
• Make get() return either function return value or STDOUT.
• Make .stdout, .stderr, and .exitcode handling more robust.
• Add link from .err to .stderr.
• Alter test suite to work with new output API.
• Add script to make multiple virtualenv testing easier