There are a ton related to performance, which you can probably skip for now. Those should be reviewed with a fine-toothed comb, since most performance fixes make the code harder to read, unfortunately.
This one is kind of a big deal for pouchdb-server. Basically I wanted to set it up so that when we test against pouchdb-server, we don't cram all the files in the root directory (annoying during development), and in the process I discovered a bug in how the db was reporting its name in db.info. This fix makes sure that the name is the same everywhere (on('destory'), on('create'), db.info()) and is something sensible, regardless of the prefix.
More pouchdb-server stuff. I think it makes sense to go ahead and merge this, even though it's failing. Gives us an excuse to make more improvements to MemDOWN.