Clarify specification of the origin point for glyph cut-outs

[dspreadbury]

Reported by Erik Ronström. Regarding cut-outs, the SMuFL spec says:

Each cut-out is specified as a pair of X,Y coordinates (in spaces), describing the innermost corner of a nominal rectangle that intersects the bounding box. For example, cutOutNE specifies the bottom left corner of a rectangle that intersects the top right corner of the bounding box of the glyph. The positions of each of the other corners of the cut-out rectangle are calculated using the bounding box of the glyph.

However, it doesn’t explicitly state the origin of the coordinate system. IMO, it would make most sense to use the same origin as the glyph’s origin. But using the metadata for Bravura 1.204, this gives wrong results. It looks like the cut-outs in Bravura are instead measured from the bottom-left corner of of the glyph’s bounding box.

The spec should be clarified to make this relationship clear.

[lpugin]

How does this relate to #71 ? Are you suggesting to change (back?) to the glyph origin? I think it would indeed be more inline with what font editors normally produce.

[dspreadbury]

It doesn't change anything about #71: it simply entails making it explicit in the spec what point the cut-outs are relative to.

[dspreadbury]

Fixed in #98.