Chapter 7 Command for Binary code words

[twjudson]

Also in Chapter 7, but in other places that deal with code words, can you add a command for all the binary code words, such as 111, 000, etc.? Especially in aligned displays and in tables, I switch to a tabular numeral so they all have the same width and line up. Rob provides a font hook for tables, but unfortunately we don't want all tables to do this, and there are many places outside of tables where they occur.