Refactored InvariantNode and ImplicitConstraintNode to inherit the interfaces (classes with only virtual member functions) IInvariantNode and IImplicitConstraintNode respectively.
Changed NULL_ID and NULL_NODE_ID to be the maximum size_t instead of 0
Renamed VarId to VarViewId to indicate that it is either a variable id or a variable view id.
Renamed VarIdBase to VarId
Added ViewId
Changed VarNodeId, VarId (previously VarIdBase), ViewId, and InvariantId into size_t
Changed InvariantNodeId such that the left-most bit indicates if the id represents an implicit constraint or an invariant
Changed VarViewId such that the left-most bit indicates if the id represents a view or a variable
NULL_IDandNULL_NODE_IDto be the maximumsize_tinstead of 0VarIdtoVarViewIdto indicate that it is either a variable id or a variable view id.VarIdBasetoVarIdViewIdVarNodeId,VarId(previouslyVarIdBase),ViewId, andInvariantIdintosize_tInvariantNodeIdsuch that the left-most bit indicates if the id represents an implicit constraint or an invariantVarViewIdsuch that the left-most bit indicates if the id represents a view or a variableIdMapwithvector