Change lots of macros to constexpr in Actor.h

For the purposes of type safety,  allowing the compiler to further optimize, and preventing possible name collisions, I've converted these 13 macros to constexpr's.

src/Actor.h

@@ -19,19 +19,19 @@ class LuaClass;
 typedef AutoPtrCopyOnWrite<LuaReference> apActorCommands;
 
 /** @brief The background layer. */
-#define DRAW_ORDER_BEFORE_EVERYTHING		-200
+constexpr int DRAW_ORDER_BEFORE_EVERYTHING = -200;
 /** @brief The underlay layer. */
-#define DRAW_ORDER_UNDERLAY			-100
+constexpr int DRAW_ORDER_UNDERLAY = -100;
 /** @brief The decorations layer. */
-#define DRAW_ORDER_DECORATIONS			   0
+constexpr int DRAW_ORDER_DECORATIONS = 0;
 /** @brief The overlay layer.
  *
  * Normal screen elements go here. */
-#define DRAW_ORDER_OVERLAY			+100
+constexpr int DRAW_ORDER_OVERLAY = 100;
 /** @brief The transitions layer. */
-#define DRAW_ORDER_TRANSITIONS			+200
+constexpr int DRAW_ORDER_TRANSITIONS = 200;
 /** @brief The over everything layer. */
-#define DRAW_ORDER_AFTER_EVERYTHING		+300
+constexpr int DRAW_ORDER_AFTER_EVERYTHING = 300;
 
 /** @brief The different horizontal alignments. */
 enum HorizAlign
@@ -56,24 +56,24 @@ enum VertAlign
 LuaDeclareType( VertAlign );
 
 /** @brief The left horizontal alignment constant. */
-#define align_left 0.0f
+constexpr float align_left = 0.0f;
 /** @brief The center horizontal alignment constant. */
-#define align_center 0.5f
+constexpr float align_center = 0.5f;
 /** @brief The right horizontal alignment constant. */
-#define align_right 1.0f
+constexpr float align_right = 1.0f;
 /** @brief The top vertical alignment constant. */
-#define align_top 0.0f
+constexpr float align_top = 0.0f;
 /** @brief The middle vertical alignment constant. */
-#define align_middle 0.5f
+constexpr float align_middle = 0.5f;
 /** @brief The bottom vertical alignment constant. */
-#define align_bottom 1.0f
+constexpr float align_bottom = 1.0f;
 
 // This is the number of colors in Actor::diffuse.  Actor has multiple
 // diffuse colors so that each edge can be a different color, and the actor
 // is drawn with a gradient between them.
 // I doubt I actually found all the places that touch diffuse and rely on the
 // number of diffuse colors, so change this at your own risk. -Kyz
-#define NUM_DIFFUSE_COLORS 4
+constexpr int NUM_DIFFUSE_COLORS = 4;
 
 // ssc futures:
 /*