ipa: add support for diphthongs
phonemeset: print out unrecognised characters
phonemeset: don't throw if a post-phoneme modifier occurs without a primary phoneme; print the error instead
phonemeset: support an '\#' escape sequence
phonemeset: support overriding phoneme+post_modifiers with explicit symbols
autotools: simplify the Makefile rules for the test programs
phonemeset: recognise the \x0A character in the arpabet and sampa phoneme sets
autotools: run the phonemeset tests during 'make check'
arpabet: add a space before each phoneme
arpabet: add a 'PAU' phoneme
phoneme-converter: support displaying features along side the transcription
arpabet: add the /{lng}/ feature to the transcriptions that need it
arpabet: support /l/ as well as /l<vzd>/.
arpabet: support English accents that don't rhoticize /ER/
ipa: support the /i@/ form for the /I@/ diphthong, as generated by 'espeak --ipa'
arpabet: support more phonemes for non-American accents
ipa: support the /@U/ variant of /oU/ from the 'espeak --ipa' output
arpabet: support mapping the /dz/ affricate
arpabet: remove mapping for British English diphthongs -- these do not work
arpabet: CMU dictionary does not use /AH0/ for /@/ as the note implied