Give all end-of-turn button declarations in themes a title2 attribute...

...to be used in linger mode.  Note, the C++ to implement this does not
yet exist (YogiHH says he's working on it).

data/themes/default.cfg

@@ -142,7 +142,8 @@
 
         [menu]
             id=button-endturn
-            title= _ "End Turn"
+            title=  _ "End Turn"
+            title2= _ "Advance"
             items=endturn
             ref=bottom-right-panel
             rect="=+17,=+7,+80,+20"

data/themes/dfool.cfg

@@ -159,6 +159,7 @@
         [menu]
             id=button-endturn
             title= _ "End Turn"
+            title2= _ "Advance"
             image=lite_small
             items=endturn
             ref=bottom-right-panel

data/themes/experimental.cfg

@@ -128,6 +128,7 @@
             id=button-endturn
             image=endturn-button
             #title= _ ""
+            #title2= _ ""
             items=endturn
             ref=top-right-panel
             rect="=+90,=+199,+48,+21"