This is really a much more appropriate word since it never ended up being
more than just a stack. The rename also changes the symbol names to use the
much shorter "stack".
Ditch the building of an archive (.a) in favour of linking all objects in a
directory into a lib.o file. This makes it easy to link in subdirectories
and more importantly keeps the build logic in the local subdirectories.
Note: after updating you will have to rm **/*.a if you do not make clean
before updating.
