implement new conversation list

This patch is an implementation of the conversation list using the
conversation model recently introduced in LRC.
 - Unused HistoryVC and PersonsVC are removed from the code base as we
   are switching to a one list design.
 - Setting a conversation model on SmartListVC switches the displayed
   list.
 - Actions such as selecting a conversation, double clicking, call
   button and searching are also implemented (from the LRC point of
   view which may not yet be visible for user as of this patch).
 - As the new view is based on NSTableView rather than NSOutlineView,
   a RingTableView class is introduced based on RingOutlineView code.
 - The call button at the right of the search field is removed.

Change-Id: I668f102f435048d3c85efd22d1ab31b395139215
Reviewed-by: Kateryna Kostiuk <kateryna.kostiuk@savoirfairelinux.com>
diff --git a/src/views/RingTableView.h b/src/views/RingTableView.h
new file mode 100644
index 0000000..96d4a35
--- /dev/null
+++ b/src/views/RingTableView.h
@@ -0,0 +1,48 @@
+/*
+ *  Copyright (C) 2015-2016 Savoir-faire Linux Inc.
+ *  Author: Alexandre Lision <alexandre.lision@savoirfairelinux.com>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program; if not, write to the Free Software
+ *  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301 USA.
+ */
+
+#import <Cocoa/Cocoa.h>
+
+@protocol ContextMenuDelegate;
+@protocol ContextMenuDelegate
+
+@required
+
+- (NSMenu*) contextualMenuForIndex:(NSTreeNode*) path;
+
+@end
+
+@protocol KeyboardShortcutDelegate;
+@protocol KeyboardShortcutDelegate
+
+@optional
+
+/**
+ *  This shortcut has to respond to cmd (⌘) + a
+ */
+- (void) onAddShortcut;
+
+@end
+
+@interface RingTableView : NSTableView
+
+@property (nonatomic,weak) id <ContextMenuDelegate>         contextMenuDelegate;
+@property (nonatomic,weak) id <KeyboardShortcutDelegate>    shortcutsDelegate;
+
+@end