Description: Changes the callback function signature of ArrayEach to return an error. It currently takes an error as input even though ArrayEach never passes a non-nil error into it. It should be more like ObjectEach which returns an error from its callback function.

I had to fix Dockerfile and benchmark/benchmark_codecgen.go in order to get benchmarks to run.

(...it makes this repository seem very under-maintained).

Benchmark before change: DID NOT WORK

Benchmark after change:

$ make bench
docker run -v `pwd`:/go/src/github.com/buger/jsonparser -i -t jsonparser go test  -test.benchmem -bench JsonParser ./benchmark/  -benchtime 5s -v
goos: linux
goarch: amd64
pkg: github.com/buger/jsonparser/benchmark
BenchmarkJsonParserLarge-4                    	  100000	     65332 ns/op	       0 B/op	       0 allocs/op
BenchmarkJsonParserMedium-4                   	 1000000	      9871 ns/op	       0 B/op	       0 allocs/op
BenchmarkJsonParserDeleteMedium-4             	 1000000	     10448 ns/op	       0 B/op	       0 allocs/op
BenchmarkJsonParserEachKeyManualMedium-4      	 1000000	      6816 ns/op	     112 B/op	       2 allocs/op
BenchmarkJsonParserEachKeyStructMedium-4      	 1000000	      7636 ns/op	     672 B/op	      12 allocs/op
BenchmarkJsonParserObjectEachStructMedium-4   	 1000000	     10229 ns/op	     624 B/op	      11 allocs/op
BenchmarkJsonParserSmall-4                    	10000000	      1081 ns/op	       0 B/op	       0 allocs/op
BenchmarkJsonParserEachKeyManualSmall-4       	10000000	       810 ns/op	      80 B/op	       2 allocs/op
BenchmarkJsonParserEachKeyStructSmall-4       	10000000	       935 ns/op	     144 B/op	       4 allocs/op
BenchmarkJsonParserObjectEachStructSmall-4    	10000000	       815 ns/op	     128 B/op	       3 allocs/op
BenchmarkJsonParserSetSmall-4                 	 5000000	      1593 ns/op	     816 B/op	       5 allocs/op
BenchmarkJsonParserDelSmall-4                 	 5000000	      1889 ns/op	       0 B/op	       0 allocs/op
PASS
ok  	github.com/buger/jsonparser/benchmark	113.794s