Get rid of trailing whitespace.

Commit generated by command:

find -type f ! -path '*.git*' ! -path '*.png' ! -path '*.ico' ! -path \
    '*.ogg' | xargs -I '{}' sed -i '{}' -e 's/\t*$//g' -e 's/ *$//g'

modules/corelib/ui/uiradiogroup.lua

@@ -47,7 +47,7 @@ end
 
 function UIRadioGroup:clearSelected()
   if not self.selectedWidget then return end
-  
+
   local previousSelectedWidget = self.selectedWidget
   self.selectedWidget:setChecked(false)
   self.selectedWidget = nil