Do a large chunk of the move to go

This commit moves a huge chunk of the code to go. The TODO.md document
indicates what is left to be done.

internal/fsx/touch.go

@@ -0,0 +1,25 @@
+package fsx
+
+import (
+	"os"
+	"time"
+)
+
+// Touch touches a file
+func Touch(path string) error {
+	_, err := os.Stat(path)
+	switch {
+	case os.IsNotExist(err):
+		f, err := os.Create(path)
+		if err != nil {
+			return err
+		}
+		defer f.Close()
+		return nil
+	case err != nil:
+		return err
+	default:
+		now := time.Now().Local()
+		return os.Chtimes(path, now, now)
+	}
+}