make assignments part of model

jastadd-mquat-base/src/main/jastadd/Mquat.ast

-Root ::= HardwareModel SoftwareModel Request* Objective /ILP/ ;
+Root ::= HardwareModel SoftwareModel Request* Objective /ILP/ Solution:Solution* ;
 
 // =====================================================================================================================
 // Low-Level Grammar Rules

jastadd-mquat-base/src/main/jastadd/mquat.parser

@@ -84,7 +84,7 @@ Objective objective =
   ;
 
 Root goal =
-    hardware_model.h software_model.s request.r* objective.o  {: return new Root(h,s,r,o); :}
+    hardware_model.h software_model.s request.r* objective.o  {: return new Root(h,s,r,o, new List<>()); :}
   ;
 
 MetaParameter meta_parameter =