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.

TactilityCore/Source/Log.h

@@ -2,7 +2,14 @@
 
 #include "LogMessages.h"
 
-#if CONFIG_SPIRAM_USE_MALLOC == 1 or not defined(ESP_PLATFORM)
+#ifdef ESP_TARGET
+#include <esp_log.h>
+#else
+#include <cstdarg>
+#include <cstdio>
+#endif
+
+#if not defined(ESP_PLATFORM) or (defined(CONFIG_SPIRAM_USE_MALLOC) && CONFIG_SPIRAM_USE_MALLOC  == 1)
 #define TT_LOG_ENTRY_COUNT 200
 #define TT_LOG_MESSAGE_SIZE 128
 #else
@@ -35,12 +42,6 @@ LogEntry* copyLogEntries(unsigned int& outIndex);
 
 } // namespace tt
 
-#ifdef ESP_TARGET
-#include "esp_log.h"
-#else
-#include <cstdarg>
-#include <cstdio>
-#endif
 
 #ifdef ESP_TARGET