removed sg.py file
removed sg.py file really this time, and corrected previous rm mistake by re-adding setup.py
and have now added setup.py and committed
Divided project over several files (originally the sg.py file). Made various small improvements such as alphabetical listing of experiments and fields etc under functions like ls() etc. Wrote two test scripts, one containing unit tests using the unittest module. Spacegrids is now imported as import spacegrids as sg. Improved write (to Netcdf) functionality, also by allowing the choice of NetcdfIO and Scipy here.