winmain: reworked main loop for smoother frame times.

imgui_sdl: added handling for device lost.
midi: load PINBALL.MID in uppercase and using absolute path.
Added UPS/FPS options, by default 120/60.

SpaceCadetPinball/options.h

@@ -49,12 +49,17 @@ struct optionsStruct
 	int Resolution;
 	bool UniformScaling;
 	bool LinearFiltering;
+	int FramesPerSecond;
+	int UpdatesPerSecond;
 };
 
 
 class options
 {
 public:
+	// Original does ~120 updates per second.
+	static constexpr int MaxUps = 360, MaxFps = MaxUps, MinUps = 60, MinFps = MinUps,
+	                     DefUps = 120, DefFps = 60;
 	static optionsStruct Options;
 
 	static void init();