Fixed example_geotherms

Fixed example_geotherms so as to not call B&S at too low of depth.

changed depth cutoff

Changed depth cutoff
Merge pull request #71 from lordkman/hi_timo

Fixed example_geotherms so as to not call B&S at too low of depth.
Added HP_2011_fluids
Added initialisation for HP_fluids
Modified mineral initialisation
R to constants.gas_constant
fix test output
Fix sphinx dox for eos

Fix namespace
Merge PR #72

Added database for Holland and Powell (2011) fluids with CORK EoS
Merge pull request #73 from ian-r-rose/update_sphinx_dox

Fix sphinx dox for eos

Update sphinx EOS with new directory structure
Parameter validation for modified tait
Parameter validation for CORK
Rebased, tidied