update README to say that FEniCS 1.4 is required
start to extract exchange field
pull scale attribute to state class and add step method
extract exchange field and update examples
update docs for new api, fix mathjax issue
Merge pull request #1 from micromagnetics/extract_exchange

Extract exchange field + minor API changes
fix typo in sp4
Merge branch 'master' into point_integral

Conflicts:
	README.md
	site-packages/magnumfe/llg_alouges_full_implicit.py
	site-packages/magnumfe/llg_alouges_lagrange.py
	site-packages/magnumfe/llg_alouges_project.py
	site-packages/magnumfe/state.py
	tests/llg_test.py