fixes :setDefaults for other readers

djvureader.lua

@@ -5,6 +5,7 @@ DJVUReader = UniReader:new{}
 function DJVUReader:setDefaults()
 	self.show_overlap_enable = true
 	self.show_links_enable = false
+	self.comics_mode_enable = false
 end
 
 -- check DjVu magic string to validate

koptreader.lua

@@ -295,6 +295,7 @@ end
 function KOPTReader:setDefaults()
     self.show_overlap_enable = true
     self.show_links_enable = false
+    self.comics_mode_enable = false
 end
 
 -- backup global variables from UniReader

picviewer.lua

@@ -5,6 +5,7 @@ PICViewer = UniReader:new{}
 function PICViewer:setDefaults()
 	self.show_overlap_enable = false
 	self.show_links_enable = false
+  self.comics_mode_enable = false
 end
 
 function PICViewer:open(filename)