automating setting of the equation of state
fix examples
fix user_material example
fix SolidSolution
fix test output
convert tabs to spaces
fix test
fix typos
rework Mineral.set_method

Now the method is always set to something (at least None) and the
warning to check for a change in method now works with method objects.
make EOS a new style class
fix examples and tests
Merge pull request #55 from tjhei/pull-46_setmethod

Sannes #46 with additional cleanup.

Fixes #40 .
Automatically sets the eos for minerals when defined. I took a lot of the set_methods out of the examples.
This also slightly resolves not seeing the method strings to much (Issue #8). However, it has made it more explicit what a mineral database looks like. I think the parser Ian and Bob wrote can easily be adapted. But I also think it would be an important part of the new manual. I can easily see people run into issues when they don't have the right format.