GeezerVison

This doesn't really make things much cleaner, but it works.

This was more convoluted than I expected.

Also removed some dead code from the former
(somehow the case for CacheEffect had crept back in).

This makes the PEEK/POKE sequences less jarring.

STORE_SUBSCR was alread half converted,
but wasn't using cache effects yet.

The original had mysterious `SET_TOP(NULL)` before `goto error`.
I assume those just account for `obj` having been decref'ed,
so I got rid of them in favor of the cleanup implied by `ERROR_IF()`.

This should fix the build crash on Windows.