Prepare for function abstraction.

src/Song.cpp

@@ -100,6 +100,26 @@ void Song::DetachSteps()
 		m_vpStepsByType[st].clear();
 }
 
+float Song::GetFirstSecond() const
+{
+	return this->firstSecond;
+}
+
+float Song::GetFirstBeat() const
+{
+	return this->m_SongTiming.GetBeatFromElapsedTime(this->firstSecond);
+}
+
+float Song::GetLastSecond() const
+{
+	return this->lastSecond;
+}
+
+float Song::GetLastBeat() const
+{
+	return this->m_SongTiming.GetBeatFromElapsedTime(this->lastSecond);
+}
+
 // Reset to an empty song.
 void Song::Reset()
 {
@@ -1580,22 +1600,22 @@ public:
 	static int NormallyDisplayed( T* p, lua_State *L ){ lua_pushboolean(L, p->NormallyDisplayed()); return 1; }
 	static int GetFirstSecond(T* p, lua_State *L)
 	{
-		lua_pushnumber(L, p->firstSecond);
+		lua_pushnumber(L, p->GetFirstSecond());
 		return 1;
 	}
 	static int GetLastSecond(T* p, lua_State *L)
 	{
-		lua_pushnumber(L, p->lastSecond);
+		lua_pushnumber(L, p->GetLastSecond());
 		return 1;
 	}
 	static int GetFirstBeat( T* p, lua_State *L )
 	{ 
-		lua_pushnumber(L, p->m_SongTiming.GetBeatFromElapsedTime(p->firstSecond));
+		lua_pushnumber(L, p->GetFirstBeat());
 		return 1;
 	}
 	static int GetLastBeat( T* p, lua_State *L )
 	{
-		lua_pushnumber(L, p->m_SongTiming.GetBeatFromElapsedTime(p->lastSecond));
+		lua_pushnumber(L, p->GetLastBeat());
 		return 1;
 	}
 	static int HasAttacks( T* p, lua_State *L )		{ lua_pushboolean(L, p->HasAttacks()); return 1; }

src/Song.h

@@ -231,9 +231,13 @@ public:
 	RString	m_sMusicFile;
 	RString	m_sInstrumentTrackFile[NUM_InstrumentTrack];
 
+	/** @brief The length of the music file. */
 	float	m_fMusicLengthSeconds;
+	/** @brief The first second that a note is hit. */
 	float firstSecond;
+	/** @brief The last second that a note is hit. */
 	float lastSecond;
+	/** @brief The last second of the song for playing purposes. */
 	float specifiedLastSecond;
 	float	m_fMusicSampleStartSeconds;
 	float	m_fMusicSampleLengthSeconds;
@@ -290,6 +294,11 @@ public:
 	/** @brief The Song's TimingData. */
 	TimingData m_SongTiming;
 	
+	float GetFirstBeat() const;
+	float GetFirstSecond() const;
+	float GetLastBeat() const;
+	float GetLastSecond() const;
+
 	typedef vector<BackgroundChange> 	VBackgroundChange;
 private:
 	/**