adjust lemma schema

[dwhieb]

The lemma property of the Lexeme schema should be structured as follows:

lemma:
  transcription: {Multi-Orthography Transcription}
  abstract:      {Boolean}
  unattested:    {Boolean}

This provides more information about the lemma to use when presenting it (whether to display an asterisk next to the lemma in the case of unattested/reconstructed forms, or vertical pipes for abstract forms).