Major wip refactor

Allow running without gui
Remove serialPortMultiplexer broadcast use
Add TcpServer and TcpClient
Introduce the concept of an item source

src/items/itemsource.h

@@ -0,0 +1,24 @@
+#ifndef ITEMSOURCE_H
+#define ITEMSOURCE_H
+
+#include <QObject>
+#include <vector>
+#include <memory>
+
+#include "item.h"
+
+class ItemSource : public QObject
+{
+	Q_OBJECT
+public:
+	explicit ItemSource(QObject *parent = nullptr);
+
+public slots:
+	virtual void refresh() = 0;
+
+signals:
+	void gotItems(std::vector<std::shared_ptr<Item>> items, bool inform = true);
+	void updateItems(std::vector<ItemData> items, bool inform = true);
+};
+
+#endif // ITEMSOURCE_H