Fix #11231, (append|prepend|before|after) w/ array of jQuery objects.

Closes gh-666, thanks to @rkatic!

src/manipulation.js

@@ -289,6 +289,10 @@ jQuery.fn.extend({
 	},
 
 	domManip: function( args, table, callback ) {
+
+		// Flatten any nested arrays
+		args = [].concat.apply( [], args );
+
 		var results, first, fragment, iNoClone,
 			i = 0,
 			value = args[0],