Fixed save/load, sfg creating, simulation, bug fixes

Fixed a lot of bug fixes, also added shortcut for creating signal "Space"

b_asic/GUI/arrow.py

@@ -9,12 +9,10 @@ from b_asic import Signal
 
 class Arrow(QGraphicsLineItem):
 
-    def __init__(self, source, destination, window, create_signal=True, parent=None):
+    def __init__(self, source, destination, window, signal=None, parent=None):
         super(Arrow, self).__init__(parent)
         self.source = source
-        # if an signal does not exist create one
-        if create_signal:
-            self.signal = Signal(source.port, destination.port)
+        self.signal = Signal(source.port, destination.port) if signal is None else signal
         self.destination = destination
         self._window = window
         self.moveLine()
@@ -41,6 +39,8 @@ class Arrow(QGraphicsLineItem):
                         del self._window.sfg_dict[self._window.opToSFG[operation].name]
                         self._window.opToSFG = {op: self._window.opToSFG[op] for op in self._window.opToSFG if self._window.opToSFG[op] is not self._window.opToSFG[operation]}
 
+        del self._window.signalPortDict[self]
+
     def moveLine(self):
         self.setPen(QPen(Qt.black, 3))
         self.setLine(QLineF(self.source.operation.x()+self.source.x()+14,\