espeak: extract the list of phonemes from dictsource/dict_phonemes
espeak: remove the ':' phoneme from the test data

The ':' phoneme works in conjunction with a base phoneme and as
such does not make sense on its own.
espeak: add 'espeak -x' and 'espeak --ipa' data
espeak: rework the phoneme tests

This restructures the tests to align with the data generated from
eSpeak, making it easier to compare output.