Added properties to various SDL objects

The following objects now have properties that can be user modified:
* SDL_AudioStream
* SDL_Gamepad
* SDL_Joystick
* SDL_RWops
* SDL_Renderer
* SDL_Sensor
* SDL_Surface
* SDL_Texture
* SDL_Window

src/sensor/SDL_sensor.c

@@ -393,6 +393,27 @@ SDL_Sensor *SDL_GetSensorFromInstanceID(SDL_SensorID instance_id)
     return sensor;
 }
 
+/*
+ * Get the properties associated with a sensor.
+ */
+SDL_PropertiesID SDL_GetSensorProperties(SDL_Sensor *sensor)
+{
+    SDL_PropertiesID retval;
+
+    SDL_LockSensors();
+    {
+        CHECK_SENSOR_MAGIC(sensor, 0);
+
+        if (sensor->props == 0) {
+            sensor->props = SDL_CreateProperties();
+        }
+        retval = sensor->props;
+    }
+    SDL_UnlockSensors();
+
+    return retval;
+}
+
 /*
  * Get the friendly name of this sensor
  */
@@ -500,6 +521,8 @@ void SDL_CloseSensor(SDL_Sensor *sensor)
             return;
         }
 
+        SDL_DestroyProperties(sensor->props);
+
         sensor->driver->Close(sensor);
         sensor->hwdata = NULL;
 

src/sensor/SDL_syssensor.h

@@ -45,6 +45,8 @@ struct SDL_Sensor
 
     struct sensor_hwdata *hwdata _guarded; /* Driver dependent information */
 
+    SDL_PropertiesID props _guarded;
+
     int ref_count _guarded; /* Reference count for multiple opens */
 
     struct SDL_Sensor *next _guarded; /* pointer to next sensor we have allocated */