improvments to tokenizing Scalar

- for alphanumeric sequences (optionally with [-+.]) that don't look
  like a float or int -> return as a word

  This means that '0patch' now looks like a <word> (not <label>)
  and '1.end' looks like a <word> and not <scalar>

  Something like '1-e' still does get treated as a bad <scalar> though