FreeType plugin: 'otf' extension added

Author: valid-ptr

src/osgPlugins/freetype/ReaderWriterFreeType.cpp

@@ -15,6 +15,7 @@ class ReaderWriterFreeType : public osgDB::ReaderWriter
             supportsExtension("pfb","type1 binary format");
             supportsExtension("pfa","type2 ascii format");
             supportsExtension("cid","Postscript CID-Fonts format");
+            supportsExtension("otf","OpenType format");
             supportsExtension("cff","OpenType format");
             supportsExtension("cef","OpenType format");
             supportsExtension("fon","Windows bitmap fonts format");