fix a bug in passing the error option to a profile when projecting a 2D histogram in a profile.  
fix a bug in passing the error option to a profile when projecting a 2D histogram in a profile.  

Update also the comments to document this feature in the reference doc


git-svn-id: ecbadac9c76e8cf640a0bca86f6bd796c98521e3@29748 27541ba8-7e3a-0410-8455-c3a389f83636

bbannier/ROOT,dawehner/root,dawehner/root,bbannier/ROOT,bbannier/ROOT,dawehner/root,dawehner/root,dawehner/root,bbannier/ROOT,bbannier/ROOT,dawehner/root,dawehner/root,bbannier/ROOT,bbannier/ROOT,dawehner/root