Slider: documentation comments and formatting (NFC)

Add some documentation comments to the Slider implementation.  Take the
opportunity to clean up some of the text to fit better in 80-columns,
and make ignored results explicit.

Author: compnerd

Sources/SwiftWin32/Views and Controls/Slider.swift

@@ -3,34 +3,52 @@
 
 import WinSDK
 
+/// A control for selecting a single value from a continuous range of values.
 public class Slider: Control {
   private static let `class`: WindowClass = WindowClass(named: TRACKBAR_CLASS)
   private static let style: WindowStyle =
       (base: WS_POPUP | DWORD(TBS_HORZ | TBS_TRANSPARENTBKGND), extended: 0)
 
+  // MARK - Accessing the Slider's Value
+
+  /// The slider’s current value.
   public var value: Float {
-    get { Float(SendMessageW(hWnd, UINT(TBM_GETPOS), 0, 0)) / 100.0 }
+    get {
+      Float(SendMessageW(hWnd, UINT(TBM_GETPOS), 0, 0)) / 100.0
+    }
     set(value) {
-      SendMessageW(hWnd, UINT(TBM_SETPOS), WPARAM(1), LPARAM(value * 100.0))
+      _ = SendMessageW(hWnd, UINT(TBM_SETPOS), WPARAM(1), LPARAM(value * 100.0))
     }
   }
 
+  // MARK - Accessing the Slider's Value Limits
+
+  /// The minimum value of the slider.
   public var minimumValue: Float {
-    get { Float(SendMessageW(hWnd, UINT(TBM_GETRANGEMIN), 0, 0)) / 100.0 }
+    get {
+      Float(SendMessageW(self.hWnd, UINT(TBM_GETRANGEMIN), 0, 0)) / 100.0
+    }
     set(value) {
-      SendMessageW(hWnd, UINT(TBM_SETRANGEMIN), WPARAM(1), LPARAM(value * 100.0))
+      _ = SendMessageW(self.hWnd, UINT(TBM_SETRANGEMIN),
+                       WPARAM(1), LPARAM(value * 100.0))
     }
   }
 
+  /// The maximum value of the slider.
   public var maximumValue: Float {
-    get { Float(SendMessageW(hWnd, UINT(TBM_GETRANGEMAX), 0, 0)) / 100.0 }
+    get {
+      Float(SendMessageW(self.hWnd, UINT(TBM_GETRANGEMAX), 0, 0)) / 100.0
+    }
     set(value) {
-      SendMessageW(hWnd, UINT(TBM_SETRANGEMAX), WPARAM(1), LPARAM(value * 100.0))
+      _ = SendMessageW(self.hWnd, UINT(TBM_SETRANGEMAX),
+                       WPARAM(1), LPARAM(value * 100.0))
     }
   }
 
+  // MARK -
+
   public init(frame: Rect) {
     super.init(frame: frame, class: Slider.class, style: Slider.style)
-    SendMessageW(hWnd, UINT(TBM_SETLINESIZE), WPARAM(1), LPARAM(100))
+    _ = SendMessageW(self.hWnd, UINT(TBM_SETLINESIZE), WPARAM(1), LPARAM(100))
   }
 }