split ChaingraphModelBuilder into two classes: interface and implementation
replaced clunky struct OpengmModel with some typedefs in namespace pgm
class OpengmWeightedFeature
fixed bugs in WeightedFeatureFunction
expose the builder as a parameter in Chaingraph Reasoner
added variable adders to ChaingraphModelBuilder base class
TrainableChaingraphModelBuilder stub
checkoutpoint
OpengmWeightedFactor: added add_as_feature_to method; allow different iterator types in constructor
pytraxels: added VectorOfInt
implemented TrainableChaingraphModelBuilder in terms of OpengmWeightedFeature
indesorter::reorder: more explicit error message
ChaingraphTracking: added alternative builder option