Cabalize and clean up auto-update

@kazu-yamamoto Please review. I'm going to work on a pull request to
fast-logger based on this code.
removing a warning and fixing layout.
layout only.
moving stop to outside.
flatten spawn and onErr.
flatten getCurrent.
adding comments.
using atomicModifyIORef' not to leak space.
layout only
Remove unneeded AutoUpdate (thanks @kazu-yamamoto)
Client disconnecting does not take down example #271
strictRequestBody
Add 'a'
Fix typo
Use past participles
Change advice for setting up a 'Settings' object to reflect the deprecation of the field accessors
Link to StreamingBody definition
Add space
Add 's'
Add links