wip/go-genny 20200409nb1 NetBSD

Until the Go core team include support for generics in Go, genny is a code-generation generics solution. It allows you write normal buildable and testable Go code which, when processed by the genny gen tool, will replace the generics with specific types.

* Generic code is valid Go code * Generic code compiles and can be tested * Use stdin and stdout or specify in and out files * Supports Go 1.4's go generate