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.

TactilityC/Source/tt_init.cpp

@@ -22,8 +22,7 @@ extern "C" {
 
 const struct esp_elfsym elf_symbols[] {
     // Tactility
-    ESP_ELFSYM_EXPORT(tt_app_context_get_data),
-    ESP_ELFSYM_EXPORT(tt_app_context_set_data),
+    ESP_ELFSYM_EXPORT(tt_app_register),
     ESP_ELFSYM_EXPORT(tt_app_context_get_parameters),
     ESP_ELFSYM_EXPORT(tt_app_context_set_result),
     ESP_ELFSYM_EXPORT(tt_app_context_has_result),
@@ -39,7 +38,6 @@ const struct esp_elfsym elf_symbols[] {
     ESP_ELFSYM_EXPORT(tt_bundle_put_bool),
     ESP_ELFSYM_EXPORT(tt_bundle_put_int32),
     ESP_ELFSYM_EXPORT(tt_bundle_put_string),
-    ESP_ELFSYM_EXPORT(tt_set_app_manifest),
     ESP_ELFSYM_EXPORT(tt_hal_i2c_start),
     ESP_ELFSYM_EXPORT(tt_hal_i2c_stop),
     ESP_ELFSYM_EXPORT(tt_hal_i2c_is_started),