add a few methods to GSNode (index, nextNode...)
add a few methods to GSNode (index, nextNode...)

simoncozens/GlyphsSDK,schriftgestalt/GlyphsSDK,simoncozens/GlyphsSDK,schriftgestalt/GlyphsSDK,schriftgestalt/GlyphsSDK,simoncozens/GlyphsSDK,simoncozens/GlyphsSDK