Refactor app launching (#174)

- Refactor the way apps work: Instead of a C interface, they are now C++ classes. The main reasoning is that attaching data to an app was cumbersome. Having different implementations for different kinds of apps was cumbersome too. (3 or 4 layers of manifest nesting for the TactilityC project)
- External apps are still written in C, but they get a createData/destroyData in their manifest, so:
- External apps now have their own manifest.
- All functions in the original AppManifest are removed and replaced by a single `createApp` function
- External apps now automatically register (each app individually!) when they run the first time. As a side-effect they become visible in the `AppList` app!
- Adapted all apps for the new interface.
- Adapted all internal logic for these changes (Gui, ViewPort, Loader, AppContext, AppInstance, etc.)
- Rewrote parts of Loader to use std::shared_ptr to make the code much safer.
- Added a refcount check for the `AppInstance` and `App` at the end of their lifecycle. Show warning if refcount is too high.

Tactility/Source/app/usbsettings/UsbSettings.cpp

@@ -1,6 +1,9 @@
+#include "CoreDefines.h"
+#include "app/App.h"
+#include "app/AppManifest.h"
+#include "hal/usb/Usb.h"
 #include "lvgl.h"
 #include "lvgl/Toolbar.h"
-#include "hal/usb/Usb.h"
 
 #define TAG "usb_settings"
 
@@ -10,36 +13,38 @@ static void onRebootMassStorage(TT_UNUSED lv_event_t* event) {
     hal::usb::rebootIntoMassStorageSdmmc();
 }
 
-static void onShow(AppContext& app, lv_obj_t* parent) {
-    auto* toolbar = lvgl::toolbar_create(parent, app);
-    lv_obj_align(toolbar, LV_ALIGN_TOP_MID, 0, 0);
+class UsbSettingsApp : public App {
 
-    if (hal::usb::canRebootIntoMassStorageSdmmc()) {
-        auto* button = lv_button_create(parent);
-        auto* label = lv_label_create(button);
-        lv_label_set_text(label, "Reboot as USB storage");
-        lv_obj_align(button, LV_ALIGN_CENTER, 0, 0);
-        lv_obj_add_event_cb(button, onRebootMassStorage, LV_EVENT_SHORT_CLICKED, nullptr);
-    } else {
-        bool supported = hal::usb::isSupported();
-        const char* first = supported ? "USB storage not available:" : "USB driver not supported";
-        const char* second = supported ? "SD card not mounted" : "on this hardware";
-        auto* label_a = lv_label_create(parent);
-        lv_label_set_text(label_a, first);
-        lv_obj_align(label_a, LV_ALIGN_CENTER, 0, 0);
-        auto* label_b = lv_label_create(parent);
-        lv_label_set_text(label_b, second);
-        lv_obj_align_to(label_b, label_a, LV_ALIGN_OUT_BOTTOM_MID, 0, 4);
+    void onShow(AppContext& app, lv_obj_t* parent) override {
+        auto* toolbar = lvgl::toolbar_create(parent, app);
+        lv_obj_align(toolbar, LV_ALIGN_TOP_MID, 0, 0);
+
+        if (hal::usb::canRebootIntoMassStorageSdmmc()) {
+            auto* button = lv_button_create(parent);
+            auto* label = lv_label_create(button);
+            lv_label_set_text(label, "Reboot as USB storage");
+            lv_obj_align(button, LV_ALIGN_CENTER, 0, 0);
+            lv_obj_add_event_cb(button, onRebootMassStorage, LV_EVENT_SHORT_CLICKED, nullptr);
+        } else {
+            bool supported = hal::usb::isSupported();
+            const char* first = supported ? "USB storage not available:" : "USB driver not supported";
+            const char* second = supported ? "SD card not mounted" : "on this hardware";
+            auto* label_a = lv_label_create(parent);
+            lv_label_set_text(label_a, first);
+            lv_obj_align(label_a, LV_ALIGN_CENTER, 0, 0);
+            auto* label_b = lv_label_create(parent);
+            lv_label_set_text(label_b, second);
+            lv_obj_align_to(label_b, label_a, LV_ALIGN_OUT_BOTTOM_MID, 0, 4);
+        }
     }
-
-}
+};
 
 extern const AppManifest manifest = {
     .id = "UsbSettings",
     .name = "USB",
     .icon = LV_SYMBOL_USB,
-    .type = TypeSettings,
-    .onShow = onShow
+    .type = Type::Settings,
+    .createApp = create<UsbSettingsApp>
 };
 
 } // namespace