v2.2.2: Fix more v2.1.0 seq bugs

Yikes! I really screwed up on the v2.1.0 release — didn't test it thoroughly. And I only just now noticed the bugs, after Zach Beane released a new Quicklisp.

The bugs are all in the seq code, so if you don't use seqs much, you may not see them. Nonetheless, I recommend pulling down the latest version from this site. (Clone under ~/quicklisp/local-projects/ to automatically shadow the version in Quicklisp.)