Refactoring, housekeeping, documentation

Add a class diagram. Still needs some details.
Refactor to better respect SOLID principles.
Housekeeping, move and rename classes/files.

app/include/sensor/LMSensor.h

@@ -0,0 +1,24 @@
+#ifndef HWMONSENSOR_H_
+#define HWMONSENSOR_H_
+
+#include <sensors/sensors.h>
+
+#include <sensor/Sensor.h>
+
+class LMSensor : public Sensor {
+public:
+  LMSensor(const sensors_chip_name *chipName, const sensors_feature *feature,
+           const sensors_subfeature *subfeature);
+
+  int value() override;
+  const std::string toString() const override;
+
+  json toJson() const override;
+
+private:
+  const sensors_chip_name *mChipName;
+  const sensors_feature *mFeature;
+  const sensors_subfeature *mSubFeature;
+};
+
+#endif // HWMONSENSOR_H_