Map "popularity meter" of ID3v2 tags to the generic rating field

See https://github.com/Martchus/tageditor/issues/84

CMakeLists.txt

@@ -10,7 +10,7 @@ set(META_APP_URL "https://github.com/${META_APP_AUTHOR}/${META_PROJECT_NAME}")
 set(META_APP_DESCRIPTION "C++ library for reading and writing MP4 (iTunes), ID3, Vorbis, Opus, FLAC and Matroska tags")
 set(META_VERSION_MAJOR 11)
 set(META_VERSION_MINOR 2)
-set(META_VERSION_PATCH 1)
+set(META_VERSION_PATCH 2)
 set(META_REQUIRED_CPP_UNIT_VERSION 1.14.0)
 set(META_ADD_DEFAULT_CPP_UNIT_TEST_APPLICATION ON)
 

id3/id3v2frameids.cpp

@@ -79,6 +79,8 @@ std::uint32_t convertToShortId(std::uint32_t id)
         return sRemixedBy;
     case lCopyright:
         return sCopyright;
+    case lRating:
+        return sRating;
     case lISRC:
         return sISRC;
     default:
@@ -145,6 +147,8 @@ std::uint32_t convertToLongId(std::uint32_t id)
         return lRemixedBy;
     case sCopyright:
         return lCopyright;
+    case sRating:
+        return lRating;
     case sISRC:
         return lISRC;
     default:

id3/id3v2tag.cpp

@@ -307,6 +307,8 @@ KnownField Id3v2Tag::internallyGetKnownField(const IdentifierType &id) const
         return KnownField::OriginalReleaseDate;
     case lMood:
         return KnownField::Mood;
+    case lRating:
+        return KnownField::Rating;
     case lISRC:
         return KnownField::ISRC;
     case sAlbum:
@@ -349,6 +351,8 @@ KnownField Id3v2Tag::internallyGetKnownField(const IdentifierType &id) const
         return KnownField::RemixedBy;
     case sCopyright:
         return KnownField::Copyright;
+    case sRating:
+        return KnownField::Rating;
     case sISRC:
         return KnownField::ISRC;
     default: