DOC: Clarify and prettify documentation, and some indentation in the code.
DOC: Clarify and prettify documentation, and some indentation in the code.

FrancoisRheaultUS/dipy,jyeatman/dipy,maurozucchelli/dipy,villalonreina/dipy,nilgoyyou/dipy,matthieudumont/dipy,StongeEtienne/dipy,samuelstjean/dipy,oesteban/dipy,samuelstjean/dipy,samuelstjean/dipy,rfdougherty/dipy,JohnGriffiths/dipy,maurozucchelli/dipy,StongeEtienne/dipy,demianw/dipy,mdesco/dipy,beni55/dipy,maurozucchelli/dipy,jyeatman/dipy,FrancoisRheaultUS/dipy,oesteban/dipy,rfdougherty/dipy,beni55/dipy,villalonreina/dipy,matthieudumont/dipy,nilgoyyou/dipy,sinkpoint/dipy,Messaoud-Boudjada/dipy,demianw/dipy,mdesco/dipy,sinkpoint/dipy,JohnGriffiths/dipy,Messaoud-Boudjada/dipy