fixed visual update when only unit transformations have changed

src/mol-model/structure/structure/structure.ts

src/mol-model/structure/structure/symmetry.ts

src/mol-model/structure/structure/unit.ts

src/mol-repr/structure/complex-visual.ts

src/mol-repr/structure/units-representation.ts

src/mol-repr/structure/units-visual.ts

src/mol-repr/util.ts