Value string representation public function (#469)

Fixes #468

tomltree_writepub.go

@@ -0,0 +1,6 @@
+package toml
+
+// ValueStringRepresentation transforms an interface{} value into its toml string representation.
+func ValueStringRepresentation(v interface{}, commented string, indent string, ord MarshalOrder, arraysOneElementPerLine bool) (string, error) {
+	return tomlValueStringRepresentation(v, commented, indent, ord, arraysOneElementPerLine)
+}