Add support for utils-node modules that are only run under Node.js
Add init command to initialise a wiki folder

Fixes #362
Typos and style tweaks
Remove obsolete plugins from tw5.com edition
Init command should remove any includeWikis definitions

The includeWikis references will otherwise be broken when the edition
is copied.
Extend the init command to allow editions to be merged

Now we can say “—init tw5.com clientserver” to get the tw5.com content
with the client server plugins.