Implement LVGL with SDL for simulator (#16)

* Implemented LVGL with SDL for simulator

* cleanup

* added SDL to build

* build fix

* mutex fixes

* sim app cleanup and improvements

* docs updated

* fix for sdl?

* fix for SDL cmake setup

libs/lv_drivers/indev/mousewheel.h

@@ -0,0 +1,80 @@
+/**
+ * @file mousewheel.h
+ *
+ */
+
+#ifndef MOUSEWHEEL_H
+#define MOUSEWHEEL_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/*********************
+ *      INCLUDES
+ *********************/
+#ifndef LV_DRV_NO_CONF
+#ifdef LV_CONF_INCLUDE_SIMPLE
+#include "lv_drv_conf.h"
+#else
+#include "../../lv_drv_conf.h"
+#endif
+#endif
+
+#if USE_MOUSEWHEEL
+
+#warning "Deprecated, use the SDL driver instead. See lv_drivers/sdl/sdl.c"
+
+#ifdef LV_LVGL_H_INCLUDE_SIMPLE
+#include "lvgl.h"
+#else
+#include "lvgl/lvgl.h"
+#endif
+
+#if USE_SDL_GPU
+#include "../sdl/sdl_gpu.h"
+#else
+#include "../sdl/sdl.h"
+#endif
+
+/*********************
+ *      DEFINES
+ *********************/
+
+/**********************
+ *      TYPEDEFS
+ **********************/
+
+/**********************
+ * GLOBAL PROTOTYPES
+ **********************/
+
+/**
+ * Initialize the encoder
+ */
+static inline void mousewheel_init(void)
+{
+    /*Nothing to do*/
+}
+
+/**
+ * Get encoder (i.e. mouse wheel) ticks difference and pressed state
+ * @param indev_drv pointer to the related input device driver
+ * @param data store the read data here
+ */
+static inline void mousewheel_read(lv_indev_drv_t * indev_drv, lv_indev_data_t * data)
+{
+    sdl_mousewheel_read(indev_drv, data);
+}
+
+/**********************
+ *      MACROS
+ **********************/
+
+#endif /*USE_MOUSEWHEEL*/
+
+#ifdef __cplusplus
+} /* extern "C" */
+#endif
+
+#endif /*MOUSEWHEEL_H*/