Use a more standardized project layout

In #2, mrngm made the point that we should move to a more
standardized project structure. This commit does exactly that.
The new project structure is based on the repository listed at
<https://github.com/golang-standards/project-layout>.

Fixes #2.

pkg/gobmarsh/marshal.go

@@ -0,0 +1,22 @@
+package gobmarsh
+
+// Easier marshalling to and from gob encoding
+
+import (
+	"bytes"
+	"encoding/gob"
+)
+
+func Marshal(v interface{}) ([]byte, error) {
+	b := new(bytes.Buffer)
+	err := gob.NewEncoder(b).Encode(v)
+	if err != nil {
+		return nil, err
+	}
+	return b.Bytes(), nil
+}
+
+func Unmarshal(data []byte, v interface{}) error {
+	b := bytes.NewBuffer(data)
+	return gob.NewDecoder(b).Decode(v)
+}