All dialogs now use default skin and foreground colour

(The attributes are still available in the schema though, and will not be removed.)

rsrc/dialogs/attack-friendly.xml

@@ -1,6 +1,6 @@
 <?xml version='1.0' encoding='UTF-8' standalone='no'?>
 <?xml-stylesheet href="dialog.xsl" type="text/xsl"?>
-<dialog skin='dark' defbtn='cancel'>
+<dialog defbtn='cancel'>
 	<pict type='dlog' num='10' top='6' left='6'/>
 	<text top='6' left='48' width='192' height='40'>
 		This creature isn't hostile.<br/>