an option to detect "inserted" and removed items in arrays

[DetachHead]

diff(['a', 'c', 'd', 'e'], ['a', 'b', 'c', 'd', 'e'])

the current behavior is to treat indexes 1, 2 and 3 as changed and 4 as added

{ '1': 'b', '2': 'c', '3': 'd', '4': 'e' }

it would be nice if it was able to detect that only one value was added. something like this:

{ inserts: { 1: 'b' } }

[Antti Korpi]

Duplicate?: #60 #79 #51

[DetachHead]

duplicate of #60 i guess