Code block and chat improvements (#43)

* moved toast overlay only to the chat

* used adwaita style in the sourceView
added copy button for code with toast notification
added changing source style when theme changed

* removed print

src/window.ui

@@ -27,8 +27,6 @@
       </object>
     </child>
     <property name="content">
-      <object class="AdwToastOverlay" id="main_overlay">
-        <child>
           <object class="AdwOverlaySplitView" id="split_view_overlay">
             <property name="show-sidebar" bind-source="show_sidebar_button" bind-property="active" bind-flags="sync-create"/>
             <property name="sidebar">
@@ -133,6 +131,8 @@
                     <property name="orientation">1</property>
                     <property name="vexpand">true</property>
                     <property name="hexpand">true</property>
+                    <child>
+                    <object class="AdwToastOverlay" id="main_overlay">
                     <child>
                       <object class="GtkScrolledWindow" id="chat_window">
                         <property name="propagate-natural-height">true</property>
@@ -162,7 +162,8 @@
                         </child>
                       </object>
                     </child>
-
+                    </object>
+                    </child>
                     <child>
                       <object class="AdwClamp">
                         <property name="maximum-size">1000</property>
@@ -243,8 +244,6 @@
                 </property>
               </object>
             </child>
-          </object>
-        </child>
       </object>
     </property>
     <object class="AdwPreferencesDialog" id="preferences_dialog">