Delete duplicate steps, to clean up after a bug in a previous version.

(This is more important now, as the "change duplicate difficulties"
code will make duplicate steps cause all difficulties to be shuffled around,
making it much harder to fix.)

stepmania/src/Song.cpp

@@ -491,6 +491,33 @@ static void GetImageDirListing( CString sPath, CStringArray &AddTo, bool bReturn
 	GetDirListing( sPath + ".gif", AddTo, false, bReturnPathToo ); 
 }
 
+static void DeleteDuplicateSteps( Song *song, vector<Steps*> &vSteps )
+{
+	/* vSteps have the same StepsType and Difficulty.  Delete them if they have the
+	 * same m_sDescription, m_iMeter and SMNoteData. */
+	for( unsigned i=0; i<vSteps.size(); i++ )
+	{
+		const Steps *s1 = vSteps[i];
+		for( unsigned j=i+1; j<vSteps.size(); j++ )
+		{
+			const Steps *s2 = vSteps[j];
+			if( s1->GetDescription() != s2->GetDescription() )
+				continue;
+			if( s1->GetMeter() != s2->GetMeter() )
+				continue;
+			if( s1->GetSMNoteData() != s2->GetSMNoteData() )
+				continue;
+
+			LOG->Trace("Removed duplicate steps in song \"%s\" with description \"%s\" and meter \"%i\"",
+				song->GetSongDir().c_str(), s1->GetDescription().c_str(), s1->GetMeter() );
+				
+			song->RemoveNotes(s2);
+			--j;
+		}
+	}
+}
+
+
 /* Songs in BlacklistImages will never be autodetected as song images. */
 void Song::TidyUpData()
 {
@@ -790,6 +817,11 @@ void Song::TidyUpData()
 
 			vector<Steps*> vSteps;
 			this->GetSteps( vSteps, st, dc );
+
+			/* Delete steps that are completely identical.  This happened due to a
+			 * bug in an earlier version. */
+			DeleteDuplicateSteps( this, vSteps );
+
 			SortNotesArrayByDifficulty( vSteps );
 			for( unsigned k=1; k<vSteps.size(); k++ )
 			{