Abandon additional transport method parameter

[napsy]

Most of the time, users won't care what is the underlaying communication protocol.
So, I propose:

func NewPlugin(path string, params ...string) *Plugin

To change the default communication protocol, expose:

func SetProto(proto string)

The API becomes clearer. E.g.:

p := pingo.NewPlugin("plugins/hello-world/hello-world")

[dullgiulio]

Agreed. This would also help implementing automatic switching of protocol.

[kdar]

Would be nice to use RPC over stdin/stdout too.

[dullgiulio]

@kdar: I'll make a new issue for this.