Externalize the 'difference/s' text eclipse-platform#1236

Externalization of text used in "Textmergeviewer.java" related to number
of differences shown in toolbar of compare editor using
MessageFormat.format

team/bundles/org.eclipse.compare/compare/org/eclipse/compare/contentmergeviewer/TextMergeViewer.java

@@ -5421,8 +5421,7 @@ private void updateToolbarLabel() {
 		int differenceCount = fMerger.changesCount();
 		if (tbm != null) {
 
-			String label = differenceCount > 1 ? differenceCount + " Differences" //$NON-NLS-1$
-					: differenceCount == 1 ? differenceCount + " Difference" : "No Difference"; //$NON-NLS-1$ //$NON-NLS-2$
+			String label = MessageFormat.format(CompareMessages.TextMergeViewer_differences, differenceCount);
 			LabelContributionItem labelContributionItem = new LabelContributionItem(DIFF_COUNT_ID,
 					label);
 

team/bundles/org.eclipse.compare/compare/org/eclipse/compare/internal/CompareMessages.java

@@ -96,6 +96,7 @@ private CompareMessages() {
 	public static String TextMergeViewer_atEnd_message;
 	public static String TextMergeViewer_atBeginning_title;
 	public static String TextMergeViewer_atBeginning_message;
+	public static String TextMergeViewer_differences;
 	public static String CompareNavigator_atEnd_title;
 	public static String CompareNavigator_atEnd_message;
 	public static String CompareNavigator_atBeginning_title;

team/bundles/org.eclipse.compare/compare/org/eclipse/compare/internal/CompareMessages.properties

@@ -81,6 +81,8 @@ TextMergeViewer_accessible_right={0} Right: {1}
 TextMergeViewer_atBeginning_message= Beginning of document reached. Continue from end?
 TextMergeViewer_accessible_ancestor=Ancestor: {0}
 
+TextMergeViewer_differences={0,choice,0#No difference|1#1 difference|1<{0} differences}
+
 CompareNavigator_atEnd_title= End Reached
 CompareDialog_commit_button=C&ommit
 CompareDialog_error_title=Error Saving Changes