gui2/tchat_log: Set size constraints to match the campaign menu,

...and add standard border size

data/gui/default/window/chat_log.cfg

@@ -12,6 +12,8 @@
         automatic_placement = "true"
         vertical_placement = "center"
         horizontal_placement = "center"
+        maximum_width = 800
+        maximum_height = 600
 
         [tooltip]
             id = "tooltip_large"
@@ -142,6 +144,8 @@
                 [/column]
                 [column]
                     grow_factor = 0
+                    border = "all"
+                    border_size = 5
                     [button]
                         id = "cancel"
                         definition = "default"