Fyrd

This version adds a much more stable local mode, a dramatic refactoring of the code into a modular structure, and a large number of bugfixes.

It is already quite stable, but there are a few outstanding issues to be addressed.

Corrects a bug where incorrect queue values were not checked

A very minor update that includes documentation and packaging changes to make this package work with PyPI.

This release consists of numerous small bug fixes and stability improvements, plus the addition of the ability to specify the executable used for slurm/torque in the config file.

All scripts that used to be in bin/ have been moved into a single
entry-point script called `fyrd` and are managed as subcommands instead
of as separate scripts.

The scripts in bin/ have thus all been converted to shell scripts that
are simple aliases of the relevant fyrd subcommands.

I made a logo of a Saxon shield of the kind used in fyrds and
superimposed a cluster tree.

In addition, I have completely overhauled the documentation and added
the logo. The documentation now builds sensibly as html and pdf, with
the new icon nicely presented in both.

To make script outputs easier to read, I now use the tabulate library,
which I have added as a new dependency.

This version changes the way outputs are retrieved from jobs.

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` All other variables (`.out`, `.stdout`, `.stderr`, and `.exitcode`) are saved 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()`.

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