[gnote] Replace std::string by Glib::ustring in ITagManager

[Aurimas Černius <aurimasc src gnome org>]

commit 26955d24a0cd2bcd37ef9a444d391f2436a6d7d9
Author: Aurimas Černius <aurisc4 gmail com>
Date:   Sat Feb 4 14:09:43 2017 +0200

    Replace std::string by Glib::ustring in ITagManager

 src/itagmanager.hpp |   12 +++++++-----
 src/tagmanager.cpp  |    8 ++++----
 src/tagmanager.hpp  |   10 +++++-----
 3 files changed, 16 insertions(+), 14 deletions(-)
---
diff --git a/src/itagmanager.hpp b/src/itagmanager.hpp
index 12908a5..115908f 100644
--- a/src/itagmanager.hpp
+++ b/src/itagmanager.hpp
@@ -1,7 +1,7 @@
 /*
  * gnote
  *
- * Copyright (C) 2013 Aurimas Cernius
+ * Copyright (C) 2013,2017 Aurimas Cernius
  *
  * 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
@@ -20,6 +20,8 @@
 #ifndef _ITAGMANAGER_HPP_
 #define _ITAGMANAGER_HPP_
 
+#include <glibmm/ustring.h>
+
 #include "tag.hpp"
 #include "base/singleton.hpp"
 
@@ -36,10 +38,10 @@ public:
 
   virtual ~ITagManager();
 
-  virtual Tag::Ptr get_tag(const std::string & tag_name) const = 0;
-  virtual Tag::Ptr get_or_create_tag(const std::string &) = 0;
-  virtual Tag::Ptr get_system_tag(const std::string & tag_name) const = 0;
-  virtual Tag::Ptr get_or_create_system_tag(const std::string & name) = 0;
+  virtual Tag::Ptr get_tag(const Glib::ustring & tag_name) const = 0;
+  virtual Tag::Ptr get_or_create_tag(const Glib::ustring &) = 0;
+  virtual Tag::Ptr get_system_tag(const Glib::ustring & tag_name) const = 0;
+  virtual Tag::Ptr get_or_create_system_tag(const Glib::ustring & name) = 0;
   virtual void remove_tag(const Tag::Ptr & tag) = 0;
   virtual void all_tags(std::list<Tag::Ptr> &) const = 0;
 };
diff --git a/src/tagmanager.cpp b/src/tagmanager.cpp
index 596cb22..a41b9ea 100644
--- a/src/tagmanager.cpp
+++ b/src/tagmanager.cpp
@@ -64,7 +64,7 @@ namespace gnote {
   // Return an existing tag for the specified tag name.  If no Tag exists
   // null will be returned.
   // </summary>
-  Tag::Ptr TagManager::get_tag (const std::string & tag_name) const
+  Tag::Ptr TagManager::get_tag (const Glib::ustring & tag_name) const
   {
     if (tag_name.empty())
       throw sharp::Exception("TagManager.GetTag () called with a null tag name.");
@@ -95,7 +95,7 @@ namespace gnote {
   // <summary>
   // Same as GetTag () but will create a new tag if one doesn't already exist.
   // </summary>
-  Tag::Ptr TagManager::get_or_create_tag(const std::string & tag_name)
+  Tag::Ptr TagManager::get_or_create_tag(const Glib::ustring & tag_name)
   {
     if (tag_name.empty())
       throw sharp::Exception ("TagManager.GetOrCreateTag () called with a null tag name.");
@@ -154,7 +154,7 @@ namespace gnote {
   /// <returns>
   /// A <see cref="Tag"/>
   /// </returns>
-  Tag::Ptr TagManager::get_system_tag (const std::string & tag_name) const
+  Tag::Ptr TagManager::get_system_tag (const Glib::ustring & tag_name) const
   {
     return get_tag(Tag::SYSTEM_TAG_PREFIX + tag_name);
   }
@@ -169,7 +169,7 @@ namespace gnote {
   /// <returns>
   /// A <see cref="Tag"/>
   /// </returns>
-  Tag::Ptr TagManager::get_or_create_system_tag (const std::string & tag_name)
+  Tag::Ptr TagManager::get_or_create_system_tag (const Glib::ustring & tag_name)
   {
     return get_or_create_tag(Tag::SYSTEM_TAG_PREFIX + tag_name);
   }
diff --git a/src/tagmanager.hpp b/src/tagmanager.hpp
index a9b24de..db03d36 100644
--- a/src/tagmanager.hpp
+++ b/src/tagmanager.hpp
@@ -1,7 +1,7 @@
 /*
  * gnote
  *
- * Copyright (C) 2013 Aurimas Cernius
+ * Copyright (C) 2013,2017 Aurimas Cernius
  * Copyright (C) 2009 Hubert Figuiere
  *
  * This program is free software: you can redistribute it and/or modify
@@ -44,10 +44,10 @@ class TagManager
 public:
   TagManager();
 
-  virtual Tag::Ptr get_tag(const std::string & tag_name) const override;
-  virtual Tag::Ptr get_or_create_tag(const std::string &) override;
-  virtual Tag::Ptr get_system_tag(const std::string & tag_name) const override;
-  virtual Tag::Ptr get_or_create_system_tag(const std::string & name) override;
+  virtual Tag::Ptr get_tag(const Glib::ustring & tag_name) const override;
+  virtual Tag::Ptr get_or_create_tag(const Glib::ustring &) override;
+  virtual Tag::Ptr get_system_tag(const Glib::ustring & tag_name) const override;
+  virtual Tag::Ptr get_or_create_system_tag(const Glib::ustring & name) override;
   virtual void remove_tag(const Tag::Ptr & tag) override;
   Glib::RefPtr<Gtk::TreeModel> get_tags() const
     {