Replace hardcoded threshold in reconst_csa example.
Replace hardcoded threshold in reconst_csa example.

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