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`)

TactilityCore/Include/Tactility/PubSub.h

@@ -0,0 +1,61 @@
+/**
+ * @file pubsub.h
+ * PubSub
+ */
+#pragma once
+
+#include "Mutex.h"
+#include <list>
+
+namespace tt {
+
+/** PubSub Callback type */
+typedef void (*PubSubCallback)(const void* message, void* context);
+
+/** Publish and subscribe to messages in a thread-safe manner. */
+class PubSub {
+
+private:
+
+    struct Subscription {
+        uint64_t id;
+        PubSubCallback callback;
+        void* callbackParameter;
+    };
+
+    typedef std::list<Subscription> Subscriptions;
+    uint64_t lastId = 0;
+    Subscriptions items;
+    Mutex mutex;
+
+public:
+
+    typedef void* SubscriptionHandle;
+
+    PubSub() = default;
+
+    ~PubSub() {
+        tt_check(items.empty());
+    }
+
+    /** Start receiving messages at the specified handle (Threadsafe, Re-entrable)
+     * @param[in] callback
+     * @param[in] callbackParameter the data to pass to the callback
+     * @return subscription instance
+     */
+    SubscriptionHandle subscribe(PubSubCallback callback, void* callbackParameter);
+
+    /** Stop receiving messages at the specified handle (Threadsafe, Re-entrable.)
+     * No use of `tt_pubsub_subscription` allowed after call of this method
+     * @param[in] subscription
+     */
+    void unsubscribe(SubscriptionHandle subscription);
+
+    /** Publish message to all subscribers (Threadsafe, Re-entrable.)
+     * @param[in] message message pointer to publish - it is passed as-is to the callback
+     */
+    void publish(void* message);
+};
+
+
+} // namespace