- BaseFilter must have virtual dtor
- magnitude object is not trivial, we need to manage filter lifetime
- Ensure move also moves filter object
- Clean-up using magnitude object by value in functions

- (experimental) provide generic way to read magnitude values
- expose /api/metrics with values formatted specifically for prometheus, with relay and sensor data
- small tweaks to sensor init

Example config:
```
scrape_configs:
  - job_name: 'espurna'
    metrics_path: '/api/metrics'
    params:
      apikey: ['apikeyapikey']
    static_configs:
      - targets: ['espurna-blabla.lan:80']
```
Where ESPurna side has
```
apiKey => "apikeyapikey"
apiEnabled => "1"
```

Add new V3.0 version of PZEM004T, not tested. Default to factory default address 0xf8, configurable through pzemv30Addr 8-bit number
Add 'frequency' measurement & 'hz' unit
Add pz.address that configures address
Implemented energy reset

Right now we only support a single device. No way to test this properly (mostly, how exactly we need to connect this stuff), so left as not implemented.

* wip

* template common operation

* more

* ui

* fix naming issues

* remove old constraints

* oops

* dummy sensor

* rearrange bmx280 magnitudes

* broker: declare and define per module

We no longer need to specify each Broker type in broker.h
But, we exchange that bit for explicit initialization of the instance

Define helper macros to generate boilerplate code
- namespace with Instance, Register(), Publish()
- forward Register(...) -> Instance.Register(...),
  Publish(...) -> Instance.Publish(...)

* don't check for broker when deps enable it

- general conversion from .ino modules into a separate .cpp files
- clean-up internal headers, place libraries into .h. guard .cpp with _SUPPORT flags 
- fix some instances of shared variables instead of public methods
- tweak build system to still build a single source file via os environment variable ESPURNA_BUILD_SINGLE_SOURCE

* ADC_VCC is not macro

* In esp.h ADC_VCC and ADC_TOUT is not macro, so define macro.

* ADC_VCC and ADC_TOUT fixes in utils.ino and sensors.h

* Adding support for I2C temperature and humidity sensor HDC1080 / 831R

* Added HDC1080 to test\build\sensor.h and arduino.h

* added brackets

* Revert ADC_MODE_VALUE to initial values

* Eof newline

* Eof newline

Co-authored-by: Max Prokhorov <prokhorov.max@outlook.com>

Co-authored-by: Joop Hilverink <33230021+HilverinkJ@users.noreply.github.com>

- Update sensor classes to support a generic way to store energy values
- Update sensor conversion code to deal with units and not magnitudes
- Add magnitude<->unit for sensors, generic way of defining used unit. Convert from sensor magnitude unit to the one used for display.
- Reset energy value based on index through external means (MQTT, HTTP)
- Rework energy timestamping, update webui with 'last saved' value

While this solves the energy conversion issues and we are finally seeing the real value, what I don't really like:
- KilowattHour and WattHour are separate enum tags, thus sort-of are different types altogether
- Conversion code in Energy object should probably use some generic 'ratio' calculation? (https://en.cppreference.com/w/cpp/numeric/ratio/ratio)
- We are still using runtime checks to do calculations and depend that sensor outputs only one specific value type.

Consider this a fix for energy display / storage and preliminary work on sensor.ino
Further sensor refactoring... soon.