Ignore needless frames of opts.ParseFrames

If the frame can be only one in tag,
don't take into consideration more frames with id.

Huge performance improvement, when opts.ParseFrames is set:
name                   old time/op    new time/op    delta
ParseArtistAndTitle-4    64.4µs ± 1%    19.5µs ±24%  -69.71%  (p=0.000 n=8+10)

name                   old alloc/op   new alloc/op   delta
ParseArtistAndTitle-4      844B ± 0%      812B ± 1%   -3.81%  (p=0.000 n=10+9)

name                   old allocs/op  new allocs/op  delta
ParseArtistAndTitle-4      25.0 ± 0%      17.2 ±13%  -31.20%  (p=0.000 n=10+10)

parse.go

@@ -90,23 +90,36 @@ func (tag *Tag) parseFrames(opts Options) error {
 		bodyRd := getLimitedReader(tag.reader, bodySize)
 		defer putLimitedReader(bodyRd)
 
-		// If user set opts.ParseFrames, take it into consideration.
+		// If user set opts.ParseFrames and frame ID is not there,
+		// skip this frame.
 		if len(parseIDs) > 0 && !parseIDs[id] {
 			if err := skipReaderBuf(bodyRd, buf); err != nil {
 				return err
 			}
 			continue
 		}
 
-		// Parse frame body.
 		frame, err := parseFrameBody(id, bodyRd)
 		if err != nil && err != io.EOF {
 			return err
 		}
 
-		// Add frame to tag.
 		tag.AddFrame(id, frame)
 
+		if len(parseIDs) > 0 {
+			// If the frame can be only one in tag,
+			// don't take into consideration more frames with id.
+			if !mustFrameBeInSequence(id) {
+				delete(parseIDs, id)
+
+				// And if it was last ID in parseIDs, we don't need to parse
+				// other frames, so break the parsing.
+				if len(parseIDs) == 0 {
+					break
+				}
+			}
+		}
+
 		if err == io.EOF {
 			break
 		}