Removed the color_adjustment_resetter

This is unused as of fa5e7fe. I'll probably need to add a different type of resetter for the ToD dialog, but for
now this isn't needed anymore.

src/image.cpp

@@ -701,16 +701,6 @@ void set_color_adjustment(int r, int g, int b)
 	}
 }
 
-color_adjustment_resetter::color_adjustment_resetter()
-	: r_(red_adjust), g_(green_adjust), b_(blue_adjust)
-{
-}
-
-void color_adjustment_resetter::reset()
-{
-	display::get_singleton()->adjust_color_overlay(r_, g_, b_);
-}
-
 void set_team_colors(const std::vector<std::string>* colors)
 {
 	if (colors == nullptr)

src/image.hpp

@@ -166,15 +166,6 @@ namespace image {
 	///for representing day/night. Invalidates all scaled images.
 	void set_color_adjustment(int r, int g, int b);
 
-	class color_adjustment_resetter
-	{
-		public:
-			color_adjustment_resetter();
-			void reset();
-		private:
-			int r_, g_, b_;
-	};
-
 	///set the team colors used by the TC image modification
 	///use a vector with one string for each team
 	///using nullptr will reset to default TC