Properly initialise WeakRefs, and remove when deallocating VarDecl
Properly initialise WeakRefs, and remove when deallocating VarDecl

jjdekker/libminizinc,tias/libminizinc,nathanielbaxter/libminizinc,jjdekker/libminizinc,nathanielbaxter/libminizinc,tias/libminizinc,jjdekker/libminizinc,nathanielbaxter/libminizinc,nathanielbaxter/libminizinc,jjdekker/libminizinc