The SI prefixes "k", "M", "G" mean "10^3", "10^6", "10^9".
The IEC prefixes "Ki", "Mi", "Gi" mean "2^10", "2^20", "2^30".
Let's use the correct name, at least in code.
Only changes the name of the constants, no other behavior change.
In C++, it's invalid to cast a block of memory to a complex type without
invoking its constructor. It's even more invalid to simply cast a pointer to a
block of memory to a pointer to *an abstract type*.
To fix this, make sure FreelistEntry is a concrete type, and call its
constructor whenever appropriate.
We now scan the stack and CPU registers for potential pointers into the
GC heap, and include any valid Cell pointers in the set of roots.
This works pretty well but we'll also need to solve marking of things
passed to native functions, since those are currently in Vector<Value>
and the Vector storage is on the heap (not scanned.)
