Commit 24c6b2450c fixes a problem with 'text mode output, but "io.scm"
needed to be sync'ed for that repair to take effect. The repair
exposed a problem with position counting for 'text mode input, which
is repaied here.
This commit includes a relatively unrelated repair to `_list` and
`_vector`, which was exposed by a combination of the I/O demo
bootstrap and a recent repair for `malloc` to recognizes `_bytes` as a
GCable type.
ebb4ce990e