+ added a method to find the common ancestor for a set of given types
+ added a method to find the common ancestor for a set of given types

devatwork/Premotion-Mansion,devatwork/Premotion-Mansion,devatwork/Premotion-Mansion,Erikvl87/Premotion-Mansion,devatwork/Premotion-Mansion,Erikvl87/Premotion-Mansion,Erikvl87/Premotion-Mansion,Erikvl87/Premotion-Mansion