Started implementing flags to handle the sharing mode.

What works:
- the gui shows the flags in ShareManager
- the flags are loaded/saved to ft_shared.cfg and passed on to FileIndexMonitor
What does not work yet:
- the flags are not accounted for yet by FileIndexMonitor

In addition:
- simplified the directories dialog in Preferences, so that it calls the ShareManager instead of dupplicating the directories management 
code that becomes larger.
- setup the ShareManager to be a singleton, so as to coherently call it from different places.




git-svn-id: http://svn.code.sf.net/p/retroshare/code/trunk@1486 b45a01b8-16f6-495d-af2f-9b41ad6348cc

retroshare-gui/src/gui/MessengerWindow.cpp

@@ -370,8 +370,7 @@ void MessengerWindow::showMessagesPopup()
 /** Shows Share Manager */
 void MessengerWindow::openShareManager()
 {
-    static ShareManager* sharemanager = new ShareManager(this);
-    sharemanager->show();
+	ShareManager::showYourself();
 
 }