ARPABETMapper generates phones that are not part of ARPABET

The `ARPABETMapper` class seems to map some IPA phones to phones that are not part of ARPABET.
So far I've seen the following examples: `{'EA', 'IA', 'OH', 'Q', 'UA'}`

Code to reproduce:

```
from ipapy.arpabetmapper import ARPABETMapper
amapper = ARPABETMapper()
amapper.map_unicode_string('o' + 'ʔ', ignore=True, return_as_list=True)

# OUTPUT: ['OH', 'Q']
```

