MINOR: tools: do not sum squares of differences for word fingerprints

MINOR: tools: do not sum squares of differences for word fingerprints

While sums of squares usually give excellent results in fixed-sise
patterns, they don't work well to compare different sized ones such
as when some sub-words are missing, because a word such as "server"
contains "er" twice, which will rsult in an extra distance of at
least 4 for just this e->r transition compared to another one missing
it. This is one of the main reasons why "show conn" only proposes
"show info" on the CLI. Maybe an improved approach consisting in
using squares only for exact same lengths would work, but it would
still make it difficult to spot reversed characters.