Generalized ExtensionSubstitutionSubtable.as
- ExtensionSubstitutionSubtable.as is now ExtensionSubtable.as
- ExtensionSubstitutionSubtableParser.as is now ExtensionSubtableParser.as
- ExtensionSubtableParser.as now accepts ScriptFeatureLookupTableParser to cover both glyph substitution table parser and glyph positioning parser.
- GlyphPositioningTableParser.as now uses the ExtensionSubtableParser.as