TimingData: add allowEmpty parameter to TidyUpData. always false for now...

src/NotesLoaderBMS.cpp

@@ -1002,7 +1002,7 @@ bool BMSChartReader::ReadNoteData()
 	delete holdStart;
 	delete lastNote;
 
-	td.TidyUpData();
+	td.TidyUpData( false );
 	out->SetNoteData(nd);
 	out->m_Timing = td;
 	out->TidyUpData();

src/ScreenHowToPlay.cpp

@@ -151,7 +151,7 @@ void ScreenHowToPlay::Init()
 		Steps *pSteps = SongUtil::GetClosestNotes( &m_Song, pStyle->m_StepsType, Difficulty_Beginner );
 		ASSERT_M( pSteps != NULL, ssprintf("No playable steps of StepsType '%s' for ScreenHowToPlay", StringConversion::ToString(pStyle->m_StepsType).c_str()) );
 
-		pSteps->m_Timing.TidyUpData();
+		pSteps->m_Timing.TidyUpData( false );
 		NoteData tempNoteData;
 		pSteps->GetNoteData( tempNoteData );
 		pStyle->GetTransformedNoteDataForStyle( PLAYER_1, tempNoteData, m_NoteData );

src/Song.cpp

@@ -537,11 +537,11 @@ void Song::TidyUpData( bool fromCache, bool /* duringCache */ )
 		m_fMusicLengthSeconds = 0;
 	}
 
-	m_SongTiming.TidyUpData();
+	m_SongTiming.TidyUpData( false );
 	
 	FOREACH( Steps *, m_vpSteps, s )
 	{
-		(*s)->m_Timing.TidyUpData();
+		(*s)->m_Timing.TidyUpData( false );
 	}
 
 	/* Generate these before we autogen notes, so the new notes can inherit

src/TimingData.cpp

@@ -863,8 +863,13 @@ float TimingData::GetDisplayedSpeedPercent( float fSongBeat, float fMusicSeconds
 
 }
 
-void TimingData::TidyUpData()
+void TimingData::TidyUpData(bool allowEmpty)
 {
+	// Empty TimingData is used to implement steps with no timing of their
+	// own.  Don't override this.
+	if( allowEmpty && empty() )
+		return;
+
 	// If there are no BPM segments, provide a default.
 	vector<TimingSegment *> *segs = m_avpTimingSegments;
 	if( segs[SEGMENT_BPM].empty() )

src/TimingData.h

@@ -378,8 +378,10 @@ public:
 
 	/**
 	 * @brief Tidy up the timing data, e.g. provide default BPMs, labels, tickcounts.
+	 * @param allowEmpty true if completely empty TimingData should be left
+	 *                   alone, false if it should be changed
 	 */
-	void TidyUpData();
+	void TidyUpData(bool allowEmpty);
 
 	// Lua
 	void PushSelf( lua_State *L );