keyboardNavigation: Fix keys 'c' and 'v' from webView

This fixes two small bugs:
1. The JavaScript-method is called "showDiff" instead of "showDiffs"
since cfbcfc1f38. That's why the 'v' button didn't work since then.
2. Commit f05d0188fc introduced an error when trying to access
"event" for key-presses from Cocoa, which resulted in an error and
therefore made the following if-statements unreachable.

Signed-off-by: Johannes Gilger <heipei@hackvalue.de>

html/lib/keyboardNavigation.js

@@ -17,10 +17,10 @@ var handleKeys = function(event) {
 		return changeFile(true);
 	else if (event.keyCode == 38 && event.ctrlKey == true) // ctrl-up_arrow
 		return changeFile(false);
-	else if (event.keyCode == 86) {// 'v'
-		showDiffs();
-		return false;
-	}
+	else if (event.keyCode == 86) // 'v'
+		showDiff();
+	else if (event.keyCode == 67) // 'c'
+		Controller.copySource();
 	return true;
 }
 
@@ -29,12 +29,8 @@ var handleKeyFromCocoa = function(key) {
 		changeHunk(true);
 	else if (key == 'k')
 		changeHunk(false);
-	else if (event.keyCode == 40 && event.ctrlKey == true) // ctrl-down_arrow
-		changeFile(true);
-	else if (event.keyCode == 38 && event.ctrlKey == true) // ctrl-up_arrow
-		changeFile(false);
 	else if (key == 'v')
-		showDiffs();
+		showDiff();
 	else if (key == 'c')
 		Controller.copySource();
 }