Not possible to use a custom plugin

[cmelbye]

I'm attempting to add NewRelic to my Go application running on Google App Engine. As far as I can tell it's not possible to use a custom plugin instead of newrelic_platform_go.NewrelicPlugin (which would be required on App Engine) in this package because of the unexported plugin property of Agent.

This is a curious choice, because it seems as if there's already an interface in the newrelic_platform_go package (newrelic_platform_go.INewrelicPlugin) that would allow for custom plugins to be used instead of the default one. (There are a couples places in this package where an interface wouldn't work, such as line 118 of agent.go, but that seems fixable.)

Was this a conscious decision, or is it something that could be changed? If you don't think this would be a good change, forking this repository for App Engine would work, but that doesn't seem like a great solution to me.

[yvasiyarov]

@cmelbye for sure it can be changed. You can just send me pull request and I will merge it