comments on part coefficient

Lots of comments and documentation
Merge pull request #24 from burnman-project/Partition-Coef-work

comments on part coefficient
documenting examples
more doc and lots of if main  statements
Merge pull request #25 from sannecottaar/comments_examples

Comments examples
Rework seismic.py

change class name to Seismic1DModel
add comments
put gravity reading in init
change grav() to gravity()

(This is a combination of 13 commits)
rename seismic.RadiusTable to seismic.SeismicRadiusTable
Add a bunch of documentation for EOS stuff.
Add a bit more doc
Merge pull request #26 from ian-r-rose/augment_eos_docs

Augment eos docs
update documentation for example_composition
implement __version__ and use it

use __version__ in distutils and sphinx
update changelog
update readme.txt
fix versioning stuff for distutils
add gitattributes for releases
update homepage
fix download link
bump version info
Add initial versions of tutorials