Morse: Table-ise splits test.
Morse: Drop AnyVal on Morse/PlainChar, will always be in a Vector.
Morse: Add MixedChar sealed trait.
Morse: s/Text/Word/ & MixedWord.
MorseSpec: Move empty case to end of table for ease of commenting out.
Morse: s/Word/Chars/ - word implies a real word.
pkg: Add AnyW.maybe(A =?> B): Option[B].
pkg: Add VectorW.splitAtLast: (Vector[A], Option[B]).
pkg: Add VectorW[A].add[A1 >: A](A1): Vector[A1].
pkg: Add VectorW[A].addOpt[A1 >: A](Option[A1]): Vector[A1].