Update: If there is no sorting methods for the column type, use string

- In the case of filtering, if there is no filtering extension for the
  column type, then the basic string based filter formatting is
  performed (i.e. string is always the fallback - there can't be an
  error because a function isn't there).

- This commit matches that behaviour in sorting. If you define a column
  type as something for which there is no column sorting function, then
  the string type will be used rather than resulting in a javascript
  error.

.datatables-commit-sync

@@ -1 +1 @@
-f8646eb57de32debca88e1a6303b5dd94cd9ed58
+5f6a92db1e86a9bd89f2bd2247e8882dabc1b3d8

media/js/jquery.dataTables.js

@@ -3988,7 +3988,7 @@
 				// methods.
 				displayMaster.sort( function ( a, b ) {
 					var
-						x, y, k, l, test, sort,
+						x, y, k, l, test, sort, fn,
 						len=aSort.length,
 						dataA = aoData[a]._aSortData,
 						dataB = aoData[b]._aSortData;
@@ -3999,7 +3999,8 @@
 						x = dataA[ sort.col ];
 						y = dataB[ sort.col ];
 	
-						test = oExtSort[ sort.type+"-"+sort.dir ]( x, y );
+						fn = oExtSort[ sort.type+"-"+sort.dir ] || oExtSort[ "string-"+sort.dir ];
+						test = fn( x, y );
 						if ( test !== 0 ) {
 							return test;
 						}