Rounded caps for straight line connections, flat for splines

Previous square cap style caused it to be drawen slightly out of end
point, and that part sometimes appeared above port, sometimes not
(usually if you select one port, connection covers port on another
side).

src/patchcanvas.py

@@ -1400,7 +1400,9 @@ class CanvasLine(QGraphicsLineItem):
         elif port_type2 == PORT_TYPE_MIDI_ALSA:
             port_gradient.setColorAt(pos2, canvas.theme.line_midi_alsa_sel if self.m_lineSelected else canvas.theme.line_midi_alsa)
 
-        self.setPen(QPen(port_gradient, 2))
+        pen = QPen(port_gradient, 2)
+        pen.setCapStyle(Qt.RoundCap)
+        self.setPen(pen)
 
     def paint(self, painter, option, widget):
         painter.save()
@@ -1505,7 +1507,9 @@ class CanvasBezierLine(QGraphicsPathItem):
         elif port_type2 == PORT_TYPE_MIDI_ALSA:
             port_gradient.setColorAt(pos2, canvas.theme.line_midi_alsa_sel if self.m_lineSelected else canvas.theme.line_midi_alsa)
 
-        self.setPen(QPen(port_gradient, 2))
+        pen = QPen(port_gradient, 2)
+        pen.setCapStyle(Qt.FlatCap)
+        self.setPen(pen)
 
     def paint(self, painter, option, widget):
         painter.save()
@@ -1539,6 +1543,7 @@ class CanvasLineMov(QGraphicsLineItem):
         else:
             qWarning("PatchCanvas::CanvasLineMov(%s, %s, %s) - invalid port type" % (port_mode2str(port_mode), port_type2str(port_type), parent))
             pen = QPen(Qt.black)
+        pen.setCapStyle(Qt.RoundCap)
 
         self.setPen(pen)
 
@@ -1596,6 +1601,7 @@ class CanvasBezierLineMov(QGraphicsPathItem):
         else:
             qWarning("PatchCanvas::CanvasBezierLineMov(%s, %s, %s) - invalid port type" % (port_mode2str(port_mode), port_type2str(port_type), parent))
             pen = QPen(Qt.black)
+        pen.setCapStyle(Qt.FlatCap)
 
         self.setBrush(QColor(0, 0, 0, 0))
         self.setPen(pen)