make stringy print out multiple strings with the same metric separately, plus print out the length of each string
truncate the string we print out, plus update the explanation
Also parse W objects
In simple mode for GC find_roots, remove <no private> from the end of things, and truncate really long node labels.

Also, for string target mode, match prefixes in addition to perfect matches,
and print out how many string targets were found.
Add a way to trigger --string-mode from the command line