Create entropy metric which takes into account the length of the string

[daanraman]

Test how well entropy per character would work to not bias towards reporting of longer names

[maximilienroberti]

@daanraman Regarding this and this, it seems that this issue is resolved. Can we close this issue or it's related to another kind of metric than just metric=lenght? I also found that pull request from Jesse that never had been merged.