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_mutex.h

@@ -0,0 +1,48 @@
+#pragma once
+
+#include <freertos/FreeRTOS.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include <stdint.h>
+#include <stdbool.h>
+
+/** A handle that represents a mutex instance */
+typedef void* MutexHandle;
+
+enum TtMutexType {
+    MUTEX_TYPE_NORMAL,
+    MUTEX_TYPE_RECURSIVE
+};
+
+/**
+ * Allocate a new mutex instance
+ * @param[in] type specify if the mutex is either a normal one, or whether it can recursively (re)lock
+ * @return the allocated instance
+ */
+MutexHandle tt_mutex_alloc(enum TtMutexType type);
+
+/** Free up the memory of the specified mutex instance. */
+void tt_mutex_free(MutexHandle handle);
+
+/**
+ * Attempt to lock a mutex.
+ * @param[in] handle the handle that represents the mutex instance
+ * @param[in] timeout the maximum amount of ticks to wait when trying to lock
+ * @return true when the lock was acquired
+ */
+bool tt_mutex_lock(MutexHandle handle, TickType_t timeout);
+
+/**
+ * Attempt to unlock a mutex.
+ * @param[in] handle the handle that represents the mutex instance
+ * @param[in] timeout the maximum amount of ticks to wait when trying to unlock
+ * @return true when the lock was unlocked
+ */
+bool tt_mutex_unlock(MutexHandle handle);
+
+#ifdef __cplusplus
+}
+#endif