Help: Open example documentation in extra window

Also remove the hack that HelpManager::handleHelpRequest looks
for ?view=split in the URL and use an enum instead.

Change-Id: I4ad74775381cf0b321181358266d8e89c6e277b5
Reviewed-by: Karsten Heimrich <karsten.heimrich@digia.com>

src/plugins/help/helpconstants.h

@@ -42,13 +42,6 @@ enum {
     ShowLastPages = 2
 };
 
-enum {
-    SideBySideIfPossible = 0,
-    SideBySideAlways = 1,
-    HelpModeAlways = 2,
-    ExternalHelpAlways = 3
-};
-
 static const QLatin1String ListSeparator("|");
 static const QLatin1String DefaultZoomFactor("0.0");
 static const QLatin1String AboutBlank("about:blank");