FL-528 GUI: View, ViewDispather. Dolphin: first start. (#276)

* GUI: view. Flooper-blooper fix compilation error.
* GUI: view and viewdispatcher bones
* GUI: view implementation, view models, view dispatcher
* GUI: view navigation, model refinement. Power: use view, view dispatcher.
* HAL Flash: proper page write. Dolphin: views. Power: views
* Dolphin: transition idle scree to Views
* Dolphin: input events on stats view. Format sources.
* HAL: flash erase. Dolphin: permanent state storage.
* Dolphin: first start welcome. HAL: flash operation status, errata 2.2.9 crutch.

firmware/targets/f4/Src/main.c

@@ -122,6 +122,8 @@ int main(void)
   delay_us_init_DWT();
   api_hal_vcp_init();
   api_hal_spi_init();
+  // Errata 2.2.9, Flash OPTVERR flag is always set after system reset
+  __HAL_FLASH_CLEAR_FLAG(FLASH_FLAG_ALL_ERRORS);
   /* USER CODE END 2 */
 
   /* Init scheduler */