Better PageUp / PageDown

Makes PageUp/PageDown scroll to maintain cursor position relative to the viewport (matching the behavior of Visual Studio, Sublime Text, JetBrains IDEs, and others).

Without this extension, if your cursor is at the top of the viewport and you press PageDown, it will simply move to the bottom of the viewport, without scrolling any new code into view. With this extension, your cursor will move to the same line number, but the viewport will scroll so that it stays where it was on your screen (in this example, at the top).