refactoring. Everything is pointer.

src/system/pins.cpp

@@ -1,7 +1,16 @@
 #include "pins.hpp"
 
-Pin::Pin(std::string name) : SystemElement(name) {};
+Pin::Pin(std::string name) : SystemElement(name), sig(nullptr) {};
+
+bool Pin::connected() {
+    return sig != nullptr;
+}
+
+void Pin::connect(Signal *signal)
+{
+    sig = signal;
+}
 
 Pins::Pins(void): SystemElementContainer<Pin>("pins") {}
 
-Pins::Pins(std::vector<Pin> pins): SystemElementContainer<Pin>("pins", pins) {}
+Pins::Pins(std::vector<Pin *> pins): SystemElementContainer<Pin>("pins", pins) {}