Add validation for new bits of FluxObjective

cf #403

sbml-level-3/version-1/fbc/spec/apdx-validation-v2.tex

@@ -318,8 +318,8 @@ \subsubsection*{Rules for \class{FluxObjective} object}
 (References: SBML Level~3 Version~1 Core, Section~3.2.) }
 
 \validRule{fbc-20603}{A \FluxObjective object must have the required
-attributes \token{fbc:\-reaction} and \\ \token{fbc:\-coefficient}, and may
-have the optional attributes \token{fbc:\-id} and \token{fbc:\-name}. No
+attributes \token{fbc:\-reaction}, \\ \token{fbc:\-coefficient}, and \token{fbc:\-variableType} and may
+have the optional attributes \token{fbc:\-reaction2}, \token{fbc:\-id} and \token{fbc:\-name}. No
 other attributes from the SBML Level~3 Flux Balance Constraints
 namespace are permitted on a \FluxObjective object. (References: SBML
 Level~3 Package Specification for Flux Balance Constraints, Version~2,
@@ -354,6 +354,15 @@ \subsubsection*{Rules for \class{FluxObjective} object}
 Package Specification for Flux Balance Constraints, Version~2,
 \sec{model-class}.) }
 
+\validRule{fbc-20609}{The value of the attribute \token{fbc:\-variableType} of a \FluxObjective object must be either \val{linear} or \val{quadratic}. (References: SBML
+Level~3 Package Specification for Flux Balance Constraints, Version~2,
+\sec{fluxobjective-class}.) }
+
+\validRule{fbc-20650}{If the \token{fbc:\-reaction2} attribute of a \FluxObjective object is defined, its \token{fbc:\-variableType} attribute must have the value \val{quadratic}. (References: SBML
+Level~3 Package Specification for Flux Balance Constraints, Version~2,
+\sec{fluxobjective-class}.) }
+
+
 
 \subsubsection*{Rules for extended \class{Reaction} object}