Revisit glyhpnames to work with Glyphs app naming convention

Our use of underscore is not compatible with Glyphsapp convention. 

```
one_zerolith-sinhala
two_zerolith-sinhala
three_zerolith-sinhala
four_zerolith-sinhala
five_zerolith-sinhala
six_zerolith-sinhala
seven_zerolith-sinhala
eight_zerolith-sinhala
nine_zerolith-sinhala

```