[WIP Don't merge] Change `Replace "-" with "+"` to `Replace "-" with "+~"`

[oxygen-dioxide]

This change is suggested at https://discord.com/channels/551606189386104834/1144559877696532480

In other synthesizers, a pure - usually means a slur note instead of a new syllable, so converting them to +~ is usually better. This won't affect phonemizers for monosyllabic languages like Chinese and Japanese, because they treat +~ as +.