Allow color modulation of sprites, refactor renderer init

data/shaders/sprite.frag.glsl

@@ -4,8 +4,9 @@ in vec2 texCoord;
 out vec4 color;
 
 uniform sampler2D tex;
+uniform vec4 spriteColor;
 
 void main()
 {
-	color = texture(tex, texCoord);
+	color = spriteColor * texture(tex, texCoord);
 }