Project restructuring (fixes macOS builds) (#198)

- Create `Include/` folder for all main projects
- Fix some issues here and there (found while moving things)
- All includes are now in `Tactility/` subfolder and must be included with that prefix. This fixes issues with clashing POSIX headers (e.g. `<semaphore.h>` versus Tactility's `Semaphore.h`)

TactilityC/Include/tt_init.h

@@ -0,0 +1,15 @@
+#pragma once
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * Initialization method for TactilityC
+ * @warning This is called from the main firmware. Don't call this from an external app!
+ */
+void tt_init_tactility_c();
+
+#ifdef __cplusplus
+}
+#endif