Covers basic literal and delta application. Input files were created by
using dd and the 'conv=notrunc' option to modify sections of files
created from /dev/urandom. All file start with two null bytes to
convince Git they are binary.
Conflict errors are now represented by an exported type that is
compatible with errors.Is instead of using the method defined on
ApplyError. This makes the tests slightly cleaner and should be more
idiomatic for clients.