Begin sandboxing support, README updates.

sandbox/sandboxfactory.h

@@ -0,0 +1,11 @@
+#ifndef SANDBOXFACTORY_H
+#define SANDBOXFACTORY_H
+#include <memory>
+#include "sandbox.h"
+#include "sandbox-linux.h"
+#include "sandbox-openbsd.h"
+inline std::unique_ptr<Sandbox> createSandbox()
+{
+	return std::make_unique<SandboxLinux>();
+}
+#endif