Allow using -f option to also specify a library of specifications

[davidm-mm]

.. rather than immediately printing them, they can then be referenced by name on the commandline.

For simplicity, I use the ';' as the separator between name and specification. If such a character is present, then the dictionary of builtin protocols is extended. Otherwise the line is treated as a standard specification and queued for display.

I've neglected to update the changelog, it looks like this is done post-merge?