Add `switch` command

Change-Id: I5db53925f1710e29b49398621e6b634889f1df15
diff --git a/src/interpreter.cpp b/src/interpreter.cpp
index 3f8edc7..43e2269 100644
--- a/src/interpreter.cpp
+++ b/src/interpreter.cpp
@@ -247,6 +247,11 @@
     m_datastore.cancel();
 }
 
+void Interpreter::operator()(const switch_& switch_cmd) const
+{
+    m_datastore.setTarget(switch_cmd.m_target);
+}
+
 struct commandLongHelpVisitor : boost::static_visitor<const char*> {
     template <typename T>
     auto constexpr operator()(boost::type<T>) const