Merges three files into one and stores the result in a file dest. The old_file is an original version while new_file1 and new_file2 are modified versions of an original.
Path to the first file. It acts as "old" file.
Path to the second file. It acts as modified version of old_file.
Path to the third file. It acts as modified version of old_file.
Path of the resulting file, containing merged changed from both new_file1 and new_file2.
Returns true if merge was successful, string with rejected chunks if it was not or false if an internal error happened.