Go agent v3.13.0

3.13.0

Replaced the NR AWS SDK V2 integration for the v3 agent with a new version that works. See the v3/integrations/nrawssdk-v2/example/main.go file for an example of how to use it. Issues #250 and #288 are fixed by this PR. #309
Fixes issue #221: grpc errors reported in code watched by UnaryServerInterceptor() or StreamServerInterceptor() now create error events which are reported to the UI with the error message string included. #317
Fixes documentation in GUIDE.md for txn.StartExternalSegment() to reflect the v3 usage. Thanks to @abeltay for calling this to our attention and submitting PR #320.

The v3/examples/server/main.go example now uses newrelic.ConfigFromEnvironment(), rather than explicitly pulling in the license key with newrelic.ConfigLicense(os.Getenv("NEW_RELIC_LICENSE_KEY")). The team is starting to use this as a general systems integration testing script, and this facilitates testing with different settings enabled.

New Relic recommends that you upgrade the agent regularly to ensure that you're getting the latest features and performance benefits. Additionally, older releases will no longer be supported when they reach end-of-life.