MemorySpace::allocate needs to have memory pool counting.

[crtrott]

The lowest level public API for memory allocation doesn't tack allocations via profiling hooks.

• Consolidate all memory tracking to MemorySpace::allocate and MemorySpace::deallocate
• Pass the label in
• DO NOT try to recover the label from the allocation since MemorySpace::allocate can allocate memory without adding our allocation header
• allocate(size_t) and deallocate(void*, size_t) use empty label
• add allocate(const std::string, size_t) and deallocate(const std::string, void*, size_t) which are also called by the no-label overloads.
• if a label is passed to allocate it is technically a user error to not pass the same label to deallocate - though I guess a tool can recover, since the ptr has to match at least..