fixing SAPHON to IPA mapping

Do not merge yet.
- Converted all aspiration and preaspiration on voiced segments from ʰ to ʱ
- Converted all creaky diacritics on voiceless sounds to modifier glottal stops ˀ
- ejective markers on voiced segments were not touched, because none of the current SAPHON languages have such sounds... not sure why those columns were even in the spreadsheet. Any insight @bambooforest? Unless there's a compelling reason to leave them in, I'll just delete those rows in the IPA mapping.
- waiting to hear about the phoneme only found in Yurakaré (sent email)
- decided to retain the beta with downtack in Cashibo-Cacataibo, but adjusted the feature mapping to make all beta-plus-downtack phonemes to have w-like features (minus the dorsal feats. and rounding)

Closes #35