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