implemented diff3 functionality #358

Job	Run time
Build the fuzzers	39s
Run the fuzzers (fuzz_patch, true)	40s
Run the fuzzers (fuzz_cmp_args, true)	46s
Run the fuzzers (fuzz_ed, true)	38s
Run the fuzzers (fuzz_side, true)	42s
Run the fuzzers (fuzz_cmp, true)	40s
Run the fuzzers (fuzz_normal, true)	45s
	4m 50s

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