* emon: configure ratios without reboot
* settings: serialize() support
* debug: use vsnprintf from newlib, not from sdk
* settings/experimental: show defaults via `get`
* emon: override base methods, fix defaults
* sensor/emon: expose internal index calculation
- refactor configuration to use the correct index when accessing indexed
sensor methods. store index value on magnitude, refactor loops to
accomodate this new functionality
- rename slot(index) -> description(index), since we use 'slot' as
numeric value
- 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
- add experimental `relayDummy` to configure dummy relays at runtime
- add tuya-generic-dimmer #1729
- cleanup broker interface to allow Tuya module to properly receive events, modify broker methods to allow different function signatures
- add basic tests for Tuya frame and data protocol
- update every dynamicjsonbuffer with fixed size constructor argument
- change to ws callback registration to use a class builder (just cosmetic)
- test multiple ws data callbacks for each module
- remove some of the static strings in favour of ws data callback
- improve sensor ws callback data size, remove duplicated strings
- use static buffer in wsDebugSend
- postpone wsSend until loop, implement wsPost to allow other modules to queue message callbacks. remove Ticker based ws callbacks for data
- update WebUI files