Template strings

[allenap]

Ideas:

• petname %j-%v-%n would yield "$adjective-$adverb-$noun", e.g. "fully-select-airedale" (same as petname -w3).
• petname 'My %J %N would yield "My $Adjective $Noun", e.g. "My Keen Toucan" (literal text & capitalisation).
• ...

[allenap]

Could use Rust-style format strings with runtime-fmt for example. Says it requires nightly but the newest version is more than 2 years old at the time of writing so it might work on stable by now.