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/uiminiwindow.lua

@@ -81,7 +81,7 @@ function UIMiniWindow:setup()
         self:minimize()
       end
     end
-    
+
   self:getChildById('miniwindowTopBar').onDoubleClick =
     function()
       if self:isOn() then