[COMMITTED] GDL2 EOSortOrdering fixes

[David Ayers]

       * EOControl/EOSortOrdering.m: Added documentation.
       Check FOUNDATION_HAS_KVC to determine whether EONull categories
       should be applied to NSNull instead.
       ([EOSortOrdering +sortOrderingWithKey:selector:]): Use AUTORELEASE
       instead of -autorelease.
       ([EOSortOrdering -initWithKey:selector:]): Use ASSIGNCOPY instead
       of ASSIGN to set key to insure immutability.
       ([EOSortOrdering -description]): Implemented.
       ([NSArray (EOKeyBasedSorting) compareUsingSortOrderings()): New
       function.
       ([NSArray (EOKeyBasedSorting) -sortedArrayUsingKeyOrderArray:]):
       Reimplemented using [NSArray -sortedArrayUsingFunction:context:]
       with new compareUsingSortOrderings() function.
       ([NSMutableArray (EOKeyBasedSorting) -sortUsingKeyOrderArray:]):
       Reimplemented using [NSMutableArray -sortUsingFunction:context:]
       with new compareUsingSortOrderings() function.
       ([NSMutableArray -_sortUsingKeyOrder:fromIndex:count:]): Removed.

Commited

Cheers,
Dave