gui2/tchat_log: Use a separate proper label for the page number text

This replaces the page number slider with a "minimal" variant slider and
an adjacent label widget whose text we enter manually.

The label format is "<PAGE>/<COUNT>" and it's untranslatable. Hopefully
this shouldn't cause any localization issues since it's all numbers and
we currently can't use alternative numeral systems anyway.

I'm leaving the page slider's maximum_value_label attribute intact just
in case this needs to be reverted later, since it's going into the 1.12
branch too.

data/gui/default/window/chat_log.cfg

@@ -65,13 +65,25 @@
                                             border_size = 5
                                             [slider]
                                                 id = "page_number"
-                                                definition = "default"
+                                                definition = "minimal"
                                                 minimum_value = 1
                                                 maximum_value = 100
                                                 step_size = 1
+                                                # Unused, kept for 1.12 i18n in case the default slider
+                                                # variant with a label needs to be restored.
                                                 maximum_value_label = _"Last"
                                             [/slider]
                                         [/column]
+                                        [column]
+                                            grow_factor = 0
+                                            border = "all"
+                                            border_size = 5
+                                            [label]
+                                                id = "page_label"
+                                                definition = "default"
+                                                label = ""
+                                            [/label]
+                                        [/column]
                                         [column]
                                             grow_factor = 0
                                             border = "all"

src/gui/dialogs/chat_log.cpp

@@ -75,6 +75,7 @@ class tchat_log::model
 		, chat_log_history(r->build_chat_log())
 		, page(0)
 		, page_number()
+		, page_label()
 		, previous_page()
 		, next_page()
 		, filter()
@@ -90,6 +91,7 @@ class tchat_log::model
 	int page;
 	static const int COUNT_PER_PAGE = 100;
 	tslider* page_number;
+	tcontrol* page_label;
 	tbutton* previous_page;
 	tbutton* next_page;
 	ttext_box* filter;
@@ -311,6 +313,11 @@ class tchat_log::controller
 		LOG_CHAT_LOG << "Maximum value of page number slider: "
 					 << count_of_pages << std::endl;
 		model_.page_number->set_value(page + 1);
+
+		std::ostringstream cur_page_text;
+		cur_page_text << (page + 1) << '/' << std::max(1, count_of_pages);
+		model_.page_label->set_label(cur_page_text.str());
+
 		LOG_CHAT_LOG << "Exiting tchat_log::controller::update_view_from_model"
 					 << std::endl;
 	}
@@ -405,6 +412,8 @@ class tchat_log::view
 							this,
 							boost::ref(window)));
 
+		model_.page_label = &find_widget<tcontrol>(&window, "page_label", false);
+
 		LOG_CHAT_LOG << "Exiting tchat_log::view::bind" << std::endl;
 	}