start modularization

things/Device.h

@@ -0,0 +1,12 @@
+#ifndef DEVICE_H
+#define DEVICE_H
+
+class Device {
+  public:
+    // purely virtual functions, need to be implemented
+    virtual void setup() = 0;
+    virtual void homieRegister() = 0;
+    virtual void loop() = 0;
+};
+
+#endif