- shrink utils source file, move heartbeat and boot management into system
- improvise with 'heartbeat' functionality. include scheduler implementation that will
manage the per-module heartbeat callbacks with individual 'mode' and
'interval' settings. current ones are mqtt (including relays, lights, thermostat), debug and
influxdb. preserve heartbeat NONE, ONCE and REPEAT, REPEAT_STATUS is effectively a hbReport & status bit.
- mqtt heartbeat is managed through mqttHeartbeat() callbacks
- tweak mqtt callbacks to use lists instead of the vector, slighly reducing the size of the .bin
- update WebUI, include report setting and update hbMode values
- make sure general.h settings include new heartbeat,
move constant definitions outside of the header
- correctly include dependencies through the .cpp, avoid leaking
internal details.
- as a side-effect, base headers are no longer included recursively

- make sure we call run() before checking for errors, we will miss status update otherwise and lock the sensor class in the error state that it cannot recover from
- set error flag only when either bsec or bme680 report an error. ensure we show any issues reported by the library via the debug log
ref. https://gitter.im/tinkerman-cat/espurna?at=5f63a955c1d1a53705abcbe3
TODO: add custom error messages through virtual method?

Also, a minor fix to the sensors test when using 1m and 2m boards

Add support for BME680 using libalgobsec proprietary algorithms for precise Indoor Air Quality (IAQ) measurement. Unlike traditional CO2 sensors - and good ones are expensive - it measures nearly all VOCs compounds in the air (plus other gases) and compensates those measurements with its built-in temperature and humidity sensors to determine indoor air quality.

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