Merge branch 'gsub'
Merge branch 'gsub' Conflicts: libbirdfont/OpenFontFormat/ContextualLigatureCollection.vala libbirdfont/OpenFontFormat/ContextualLigatureList.vala libbirdfont/OpenFontFormat/ContextualLigatureSet.vala libbirdfont/OpenFontFormat/GsubTable.vala libbirdfont/OpenFontFormat/LigatureCollection.vala libbirdfont/OpenFontFormat/LigatureList.vala libbirdfont/OpenFontFormat/LigatureSetList.vala