Merge pull request #3722 from fjl/hexutil-text-unmarshal

common/hexutil/hexutil.go

common/hexutil/hexutil_test.go

common/hexutil/json.go

common/hexutil/json_example_test.go

common/hexutil/json_test.go

common/types.go

common/types_test.go

core/types/block.go

core/types/bloom9.go