implemented diff3 functionality #363

Job	Run time
Build the fuzzers	1m 21s
Run the fuzzers (fuzz_side, true)	44s
Run the fuzzers (fuzz_cmp_args, true)	43s
Run the fuzzers (fuzz_ed, true)	39s
Run the fuzzers (fuzz_normal, true)	46s
Run the fuzzers (fuzz_patch, true)	43s
Run the fuzzers (fuzz_cmp, true)	45s
	5m 41s

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