Tango: Update Save icons and support “savemodified” status

Change-Id: I03589895437907b9048542f07128801577fe62dc

icon-themes/tango/links.txt

@@ -538,6 +538,3 @@ cmd/lc_charbackcolor.png cmd/lc_backcolor.png
 cmd/sc_showgraphics.png cmd/sc_insertgraphic.png
 cmd/lc_showgraphics.png cmd/lc_insertgraphic.png
 
-# Modified state for the save button
-res/savemodified_small.png cmd/sc_saveas.png
-res/savemodified_large.png cmd/lc_saveas.png