Pipeline: Change Valve symbol and add abstract Valve

PamhagenSysCtrl/Helpers/Pipeline/ExternalValve.cs

@@ -0,0 +1,22 @@
+using System.Windows;
+using System.Windows.Media;
+
+namespace PamhagenSysCtrl.Helpers.Pipeline {
+    public class ExternalValve : Valve {
+
+        public override string Label { get; }
+
+        public ExternalValve(string label, double x, double y, int orientation, Func<bool> cbOpen) :
+            base(x, y, orientation, cbOpen) {
+            Label = label;
+        }
+
+        public override void Update(bool isHovering, bool isPressed) {
+            _text?.Visibility = isHovering || (App.Plant?.ManualControlMode ?? false) ? Visibility.Visible : Visibility.Hidden;
+            _triangles?.Fill =
+                !IsOpen ? PamhagenBrushes.Red :
+                IsOpen ? PamhagenBrushes.Green :
+                Highlight ?? Brushes.DarkGray;
+        }
+    }
+}