Climlab

This release includes yet more refinements to the build procedure, moving toward a fully automated build on `conda-forge` (hopefully coming in climlab release 0.6!)

Unused parts of the RRTMG_SW and RRTMG_LW source code (the `column_model` versions) have been removed from the `climlab` repository.

This version includes pristine, unmodified copies of RRTMG_SW and RRTMG_LW source code downloaded from [AER](http://rtweb.aer.com/rrtm_frame.html), along with (very slightly) modified forms of a few Fortran code files for climlab.

A few under-the-hood changes to the build procedure hopefully paving the way for automatic builds with conda-forge (stay tuned!)

The source distribution was broken in v0.5.1.

This update fixes the source distribution so the tarball available from pypi actually works.

No changes to user functionality.

Many under-the-hood changes to the wrappers for Fortran radiation components (RRTMG and CAM3) to make it easier to build the package on different systems.

Building with `python setup.py build` or `python setup.py install` now uses `numpy.distutils.core.setup` which automates the building of Fortran extensions with `f2py`.

Installing climlab from pre-built binaries using `conda` is coming in the near-future.

There are no new changes to the public API.

Major update including
- Vastly improved,simplified and **consistent** interfaces for the CAM3 and RRTMG radiation modules
- Better testing
- Better documentation
- More robust build procedure

New features include:
- The RRTMG radiation scheme
- A much-improved build process for the Fortran extension (build once at install time with `python setup.py install`, no need to rebuild for different grid dimensions)
- numerous enhancements and simplifications to the API.