Provide sticky scrolling in source editors eclipse-platform#1719

With this change, sticky scrolling is introduced into Eclipse text editors. Sticky scrolling will keep certain source code lines visible and in a fixed position on the screen as the user scrolls down the page. This technique improves user experience by keeping information within reach at all times.

The feature can be enabled via the TextEditor settings.

Provides feature for eclipse-platform#1719 and eclipse-jdt/eclipse.jdt.ui#1364

bundles/org.eclipse.ui.editors/src/org/eclipse/ui/internal/texteditor/stickyscroll/StickyScrollingHandler.java

@@ -170,4 +170,6 @@ public void dispose() {
 	//TODO: proper ruler handling: 
 	//TODO handle ruler without line line number,
 	//TODO: ruler line number positioning, 
+
+	//TODO text foreground styling on generic text editor and text editor
 }