Allow memory refinements to behave like simple renaming.
Memory refinements now carry a boolean parameter that has the following meaning: [false] : Behave like a simple renaming of memories that merely allows to permute object identifiers. It does not allow to refine memories into a more defined version. [true] : Behave like before. Objects can be injected, and memory contents can be refined into a more defined variant. We make refinements parametric in these two variant to avoid code duplication, and because the [false] variant is a special case of the [true] variant. For completeness of the executable semantics, we now use the [false] variant.