The textual line oriented change counter was fun but was not
very effective. It tended to overcount the changes. This one
changes it to a simple N-letter substring based implementation.
Signed-off-by: Junio C Hamano <junkio@cox.net>
This is to rework diffcore break/rename/copy detection code
so that it does not affected when deltifier code gets improved.
Signed-off-by: Junio C Hamano <junkio@cox.net>