*<name of pnode>
to
<name of vnode> <name of pnode>

This means that fixed vnodes may have unique names
(not just the name of the pnode they are fixed to.)

Added "-v -v" mode,
"-v" now just outputs progress without "friendly" prompts/output
or error analysis.

Fixed bizarre bug in mutation engine that was wedging the solver.
(Should also allow for expts with only 1 non-fixed node.)

Added check to skip solving altogether if there are 0 non-fixed nodes.
(this also handles the edge case of an input with no virtual nodes.)

Added check to exit with errorcode if there are more virtual nodes than
can be mapped.