Request: replace to allow escaped characters (\t, \n, etc)

[mmicheo]

Currently, a call to swift with
echo 'abcde' | sift '(.*)c(.*)' --replace='$1\n$2'
results in ab\nde. Instead of a carriage return character, it includes a '\' char followed by a 'n' char.

Expected result: replace \n with a carriage return.
ab
de