Mass: add missing value to CustomStyle.

src/Mass/Mass.h

@@ -48,6 +48,7 @@ struct CustomStyle {
     Color4 colour{0.0f};
     Float metallic = 0.0f;
     Float gloss = 0.0f;
+    bool glow = false;
 
     Int patternId = 0;
     Float opacity = 0.0f;