This updates a large number of internal symbols, function names,
and types to match the final approved terminology. Matching the
surface language terminology and the compiler internals should
make the code easier for people to understand into the future.
And move a couple of StorageImplInfo member functions into it. In
preparation for making them use an ASTContext, to avoid importing that
header into StorageImpl.h, a lightweight header.
Meghana Gupta
Tim Kientzle
Nate Chandler