Dev/go impl

first stab at a `go` based example (just h1d for now)

```sh
$ make
github.com/go-hep/dao
github.com/gbarrand/sparse_histo/go/go-hsparse
?   	github.com/gbarrand/sparse_histo/go/go-hsparse	[no test files]
 h1d.Fill(10000000) = 2.128170003s
```