Improve widths of overlines in Serbian italics.

[jmcwilliams403]

Basically making the overline span the width of the character, which is how it's treated in Southwestern Cyrillic handwriting and by extension other fonts (examples below). This also improves legibility, particularly under Quasi-Proportional, as a string of similar characters is made easier to discern where one stops and another starts; A nonsense string "итигшпшг" is provided as a hypothetical edge case.

Ѕидарски пејзаж: шугав билмез со чудење џвака ќофте и кељ на туѓ цех.
Ѕидарски пејзаж: шугав билмез со чудење џвака ќофте и кељ на туѓ цех.
г᪻ п᪻ т᪻ ѓ п́
итигшпшг

Default Monospace:

ss16 Monospace:

Default QP (Aile):

ss16 QP:

Compared to Vollkorn:

Compared to DejaVu Serif: