golint: start from gosnmp.go

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oid_count oidCount
packet_out packetOut, non_repeaters nonRepeaters
max_repetitions maxRepetitions
slice_length sliceLength
MAX_OIDS maxOids
IpAddress IPAddress
golint: gosnp.go
golint, gofmt: helper.go, misc_test.go
golint: marshal.go
fix TODO: PDUType marshal.go. go fmt
golint: misc_test.go
golint: marshal_test.go part 1
golint: marshal_test.go part 2
golint: marshal_test.go part 3
Merge branch 'master' of https://github.com/soniah/gosnmp