Fills token->varname based on context. WORD tokens use the WORD - if it
isn't actually "WORD". Other than that, a preceding constant token is
used as name.
Signed-off-by: David Lamparter <equinox@opensourcerouting.org>
Put core CLI graph stuff in lib/command_graph.[ch] and consistently
prefix all function names with "cmd_".
Signed-off-by: David Lamparter <equinox@opensourcerouting.org>