EditorManager: add a flag for embedded linenumbers

And make use of it to accept on the command line the patterns:
"filename" "+45", "filename" ":23", "filename:12" and "filename+42"

Task-Nr: QTCREATORBUG-2428

src/plugins/coreplugin/coreplugin.cpp

@@ -100,7 +100,7 @@ void CorePlugin::extensionsInitialized()
 
 void CorePlugin::remoteCommand(const QStringList & /* options */, const QStringList &args)
 {
-    m_mainWindow->openFiles(args, true);
+    m_mainWindow->openFiles(args, ICore::SwitchMode);
     m_mainWindow->activateWindow();
 }