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/textviewer/TextViewer.cpp

@@ -11,40 +11,43 @@
 
 namespace tt::app::textviewer {
 
-static void onShow(AppContext& app, lv_obj_t* parent) {
-    lv_obj_set_flex_flow(parent, LV_FLEX_FLOW_COLUMN);
-    lvgl::toolbar_create(parent, app);
+class TextViewerApp : public App {
 
-    lv_obj_t* wrapper = lv_obj_create(parent);
-    lv_obj_set_width(wrapper, LV_PCT(100));
-    lv_obj_set_flex_grow(wrapper, 1);
-    lv_obj_set_flex_flow(wrapper, LV_FLEX_FLOW_COLUMN);
-    lvgl::obj_set_style_no_padding(wrapper);
-    lvgl::obj_set_style_bg_invisible(wrapper);
+    void onShow(AppContext& app, lv_obj_t* parent) override {
+        lv_obj_set_flex_flow(parent, LV_FLEX_FLOW_COLUMN);
+        lvgl::toolbar_create(parent, app);
 
-    lv_obj_t* label = lv_label_create(wrapper);
-    lv_obj_align(label, LV_ALIGN_CENTER, 0, 0);
-    auto parameters = app.getParameters();
-    tt_check(parameters != nullptr, "Parameters missing");
-    bool success = false;
-    std::string file_argument;
-    if (parameters->optString(TEXT_VIEWER_FILE_ARGUMENT, file_argument)) {
-        TT_LOG_I(TAG, "Opening %s", file_argument.c_str());
-        if (lvgl::label_set_text_file(label, file_argument.c_str())) {
-            success = true;
+        lv_obj_t* wrapper = lv_obj_create(parent);
+        lv_obj_set_width(wrapper, LV_PCT(100));
+        lv_obj_set_flex_grow(wrapper, 1);
+        lv_obj_set_flex_flow(wrapper, LV_FLEX_FLOW_COLUMN);
+        lvgl::obj_set_style_no_padding(wrapper);
+        lvgl::obj_set_style_bg_invisible(wrapper);
+
+        lv_obj_t* label = lv_label_create(wrapper);
+        lv_obj_align(label, LV_ALIGN_CENTER, 0, 0);
+        auto parameters = app.getParameters();
+        tt_check(parameters != nullptr, "Parameters missing");
+        bool success = false;
+        std::string file_argument;
+        if (parameters->optString(TEXT_VIEWER_FILE_ARGUMENT, file_argument)) {
+            TT_LOG_I(TAG, "Opening %s", file_argument.c_str());
+            if (lvgl::label_set_text_file(label, file_argument.c_str())) {
+                success = true;
+            }
+        }
+
+        if (!success) {
+            lv_label_set_text_fmt(label, "Failed to load %s", file_argument.c_str());
         }
     }
-
-    if (!success) {
-        lv_label_set_text_fmt(label, "Failed to load %s", file_argument.c_str());
-    }
-}
+};
 
 extern const AppManifest manifest = {
     .id = "TextViewer",
     .name = "Text Viewer",
-    .type = TypeHidden,
-    .onShow = onShow
+    .type = Type::Hidden,
+    .createApp = create<TextViewerApp>
 };
 
 void start(const std::string& file) {