Updates to work with HA 2021.9+ energy topics and general improvements

[shampeon]

Fixes gadget78/inverter-homeassistant#1. Fixes gadget78/inverter-homeassistant#3. Fixes #5. Fixes #6.

Fix for missing $MQTT_SERIAL in topic names.

I also added an examples section to the README so people can add their model's settings.

I changed the state_class to work with 2021.9+.

I fixed the output of the inverter mode to not be a measurement and instead just display the mode string.

[tanqt5041]

@shampeon Hi, May I know how did u configure for this? My one always showing 0 for everything

[shampeon]

The inverter load is the how many kWh your inverter consumed on the AC output side. It's the amount of energy used by the devices you run with your inverter.

The grid consumption is the energy flowing into your house from the grid, and these inverters can't measure that. You'd need a separate energy monitor that uses CT clamps on the grid input lines.

[TheRoarman]

Hi Ian, All sounds good what you have done. Hopefully in the next week or so i'll give your changes try. Just one thing is that my VM II has three additional fields at the end of REPLY1, so I'll need to change/check that before I can fully test. My VM II includes the PV_input_watt. I'm not too sure what the other two fields are yet. They generally ZERO.

example of a diff run against my main.cpp and NED-Kelly's:

• sscanf(reply1->c_str(), "%f %f %f %f %d %d %d %d %f %d %d %d %f %f %f %d %s", &voltage_grid, &freq_grid, &voltage_out, &freq_out, &load_va, &load_watt, &load_percent, &voltage_bus, &voltage_batt, &batt_charge_current, &batt_capacity, &temp_heatsink, &pv_input_current, &pv_input_voltage, &scc_voltage, &batt_discharge_current, &device_status);
• sscanf(reply1->c_str(), "%f %f %f %f %d %d %d %d %f %d %d %d %f %f %f %d %s %d %d %d", &voltage_grid, &freq_grid, &voltage_out, &freq_out, &load_va, &load_watt, &load_percent, &voltage_bus, &voltage_batt, &batt_charge_current, &batt_capacity, &temp_heatsink, &pv_input_current, &pv_input_voltage, &scc_voltage, &batt_discharge_current, &device_status, &dummy1, &dummy2, &pv_input_watt);