Move TODO where relevant.
Describe guide environment in readme.
Extend update_ids into copy_from.

Handles a COPY FROM for each table.
Update README.
Analyze after copying from dumps.
Remove outdated TODOs.
Change link_lengths id to BIGSERIAL.

Rows were being inserted fast enough that a SERIAL could fill up in
something on the order of 13 years.
Replace lambda with list comprehension: idiomatic.