Support scrolling with page up and page down.

Author: Ehlster

Sources/Runestone/TextView/Core/Mac/TextView_Mac.swift

@@ -749,6 +749,14 @@ public extension TextView {
     override func selectAll(_ sender: Any?) {
         textViewController.selectedRange = NSRange(location: 0, length: textViewController.stringView.string.length)
     }
+
+    override func scrollPageUp(_ sender: Any?) {
+        scrollContentView.scroll(scrollContentView.visibleRect.applying(.init(translationX: 0, y: -visibleRect.height)).origin)
+    }
+
+    override func scrollPageDown(_ sender: Any?) {
+        scrollContentView.scroll(scrollContentView.visibleRect.applying(.init(translationX: 0, y: visibleRect.height)).origin)
+    }
 }
 
 // MARK: - Window