This is a step in the transition to using a common IPA-based
phoneme table for the pronunciations. It allows the base phonemes
to import the IPA versions during this transition phase.

The eSpeak code uses `end_type` for the `voicingswitch` property
when used with consonants. It also allows `endtype` to be specified
in consonants if it is the same as `starttype`.

This code adds a check in the `starttype` and `endtype` handlers
to ensure that the phoneme type has been set to preserve the
eSpeak behaviour for these properties.

The 'dontlist' feature was used by the now removed PrintPhonemesUsed
function to not display that phoneme in the list. It was also only
used by the English phonemetable.