2012-03-22: release 0.2.1. merge from integration
Merge branch 'integration'
Merge branch 'integration'
Merge branch 'integration'
Merge branch 'integration'
Merge branch 'integration'
Merge branch 'integration'
Merge branch 'integration'
Merge branch 'kreincke'
Merge branch 'kreincke'
Merge branch 'integration'
Merge branch 'kreincke'
Merge branch 'kreincke'
Merge branch 'integration'
Merge branch 'integration'
Merge branch 'integration'
Fix various typos in chapters 1-3
The G in {A,L}GPL does not stand for GNU

but for general...
Cannot should be can not in certain phrases

See http://oxforddictionaries.com/definition/english/cannot?q=cannot
On the one hand..., on the other hand...