Extract some functions from the help command

Simplify the `help' command by extracting the code into separate
functions.
Separate command operations into module

Separate and encapsulate operations on commands in their own module.
This gives a more clearly defined API to the commands and will allow
other modules to specify commands as well.
Move help command to its own module
Split known? into a couple of functions
Reorder commands
Reorder variables and procedures
Simplify list-repository-locations

Simplify `list-repository-location' by extracting the lambda's used and
defining them as separate procedures.
Simplify save-repositories-list

Simplify `save-repositories-list' by extracting some of the
functionality into its own procedures.

Since there is now a `repository-name<?' procedure the `repository<?'
procedure is renamed to `repository-location<?' for clarity and
accuracy, since that is what it really checks.
Extract print-config
Promote hookwrapper to procedure
Simplify purge command
Simplify the remove command
Extract RC loading from main