WML [message]: Add left padding when the portrait is shown on the right.

The text is now shown at exactly the same place regardless of which side
the portrait is on.

Fixes #1938.

data/gui/window/wml_message.cfg

@@ -633,7 +633,9 @@ if(gamemap_width - ({__GUI_IMAGE_WIDTH}) > {MAX_TEXT_WIDTH}
 											[column]
 
 												[spacer]
-													width = 10
+													width = "(
+if(gamemap_width - ({__GUI_IMAGE_WIDTH} + ({__GUI_IMAGE_WIDTH})) > {MAX_TEXT_WIDTH} , {__GUI_IMAGE_WIDTH} , 10)
+)"
 													height = 75
 												[/spacer]
 
@@ -645,10 +647,12 @@ if(gamemap_width - ({__GUI_IMAGE_WIDTH}) > {MAX_TEXT_WIDTH}
 
 												[spacer]
 													width = "(
-if(gamemap_width - (10 + ({__GUI_IMAGE_WIDTH})) > {MAX_TEXT_WIDTH}
-, gamemap_width - (10 + ({__GUI_IMAGE_WIDTH}) + {MAX_TEXT_WIDTH})
+if(gamemap_width - (left_padding + ({__GUI_IMAGE_WIDTH})) > {MAX_TEXT_WIDTH}
+, gamemap_width - (left_padding + ({__GUI_IMAGE_WIDTH}) + {MAX_TEXT_WIDTH})
 , 0
-))"
+)
+where left_padding = if(gamemap_width - ({__GUI_IMAGE_WIDTH} + ({__GUI_IMAGE_WIDTH})) > {MAX_TEXT_WIDTH} , {__GUI_IMAGE_WIDTH} , 10)
+)"
 													height = 75
 												[/spacer]