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/settings/Settings.cpp

@@ -13,38 +13,41 @@ static void onAppPressed(lv_event_t* e) {
     service::loader::startApp(manifest->id);
 }
 
-static void createWidget(const AppManifest* manifest, void* parent) {
+static void createWidget(const std::shared_ptr<AppManifest>& manifest, void* parent) {
     tt_check(parent);
     auto* list = (lv_obj_t*)parent;
     const void* icon = !manifest->icon.empty() ? manifest->icon.c_str() : TT_ASSETS_APP_ICON_FALLBACK;
     lv_obj_t* btn = lv_list_add_button(list, icon, manifest->name.c_str());
-    lv_obj_add_event_cb(btn, &onAppPressed, LV_EVENT_SHORT_CLICKED, (void*)manifest);
+    lv_obj_add_event_cb(btn, &onAppPressed, LV_EVENT_SHORT_CLICKED, (void*)manifest.get());
 }
 
-static void onShow(AppContext& app, lv_obj_t* parent) {
-    lv_obj_set_flex_flow(parent, LV_FLEX_FLOW_COLUMN);
+class SettingsApp : public App {
 
-    lvgl::toolbar_create(parent, app);
+    void onShow(AppContext& app, lv_obj_t* parent) override {
+        lv_obj_set_flex_flow(parent, LV_FLEX_FLOW_COLUMN);
 
-    lv_obj_t* list = lv_list_create(parent);
-    lv_obj_set_width(list, LV_PCT(100));
-    lv_obj_set_flex_grow(list, 1);
+        lvgl::toolbar_create(parent, app);
 
-    auto manifests = getApps();
-    std::sort(manifests.begin(), manifests.end(), SortAppManifestByName);
-    for (const auto& manifest: manifests) {
-        if (manifest->type == TypeSettings) {
-            createWidget(manifest, list);
+        lv_obj_t* list = lv_list_create(parent);
+        lv_obj_set_width(list, LV_PCT(100));
+        lv_obj_set_flex_grow(list, 1);
+
+        auto manifests = getApps();
+        std::sort(manifests.begin(), manifests.end(), SortAppManifestByName);
+        for (const auto& manifest: manifests) {
+            if (manifest->type == Type::Settings) {
+                createWidget(manifest, list);
+            }
         }
     }
-}
+};
 
 extern const AppManifest manifest = {
     .id = "Settings",
     .name = "Settings",
     .icon = TT_ASSETS_APP_ICON_SETTINGS,
-    .type = TypeHidden,
-    .onShow = onShow,
+    .type = Type::Hidden,
+    .createApp = create<SettingsApp>
 };
 
 } // namespace