fix for latest nightly

make force_allocation handle packed ByValPair

Mir validate

Test that &* of a dangling (and even unaligned) ptr is okay

Due to this, we are back down to 88 tests

We now lock at the "leaves" on the types, rather than locking at references.
In particular, Validate for sth. of non-reference lvalue will also lock the "outer" memory.
Also change the way we release write locks, and some refactoring in the memory.