Bug fix: handle mass hypothesis for both DsK & Dsπ


git-svn-id: svn+ssh://svn.cern.ch/reps/lhcb/Urania/trunk/PhysFit/B2DXFitters@166840 4525493e-7705-40b1-a816-d608a930855b
Define particle mass constants


git-svn-id: svn+ssh://svn.cern.ch/reps/lhcb/Urania/trunk/PhysFit/B2DXFitters@166841 4525493e-7705-40b1-a816-d608a930855b