Added tests and information about ignored id3 frames.

The ID3v2::toDict() function now has an optional
StringList* argument which will contain information
about frames that could not be converted to the dict
interface.
There are some dict tests for APE and FLAC now, and the
ID3v2 test was enlarged.

taglib/ape/apetag.cpp

@@ -197,6 +197,7 @@ void APE::Tag::fromDict(const TagDict &orig_dict)
 {
   TagDict dict(orig_dict); // make a local copy that can be modified
 
+  // see comment in toDict() about TRACKNUMBER and YEAR
   if (dict.contains("TRACKNUMBER")) {
     dict.insert("TRACK", dict["TRACKNUMBER"]);
     dict.erase("TRACKNUMBER");