Update license to BSD 2-clause

LICENSE

fact/fact.go

fact/factList.go

fact/factList_test.go

fact/fact_test.go

fact/type.go

fact/type_test.go

format/fingerprint.go

knownRounds/knownRounds.go

knownRounds/knownRounds_test.go

knownRounds/uint64Buff.go

knownRounds/uint64Buff_test.go

version/checkVersion.go

version/checkVersion_test.go