- gpio module now tracks the known providers (right now, hardware and mcp expander)
- refactored relay struct to use 'Provider' implementing setup,notify,change,boot instead of just BasePin actions
- refactored button module to use gpio provider instead of referencing types itself
- removed dual & stm code from buttons, migrate both to relay module
- added status notify and change callbacks for relayStatus (i.e. 'notify' when relay status was called, but not changed. and 'changed' when it did)  
- relays runtime configuration keys
- relay command now shows configured relays and current & target statuses
- refactor the code using relayStatus(0, blah) under LIGHT_PROVIDER check to use lightState instead
- remove rfbridge code form relay module. implement through a basic state listener in the rfbridge module, depend on RELAY_SUPPORT
- allow to bind rf codes to real relays
- drop tuya-specific lights provider, remove tuya code from relays and lights modules
- integrate tuya via relay listeners and providers, use lights custom provider
- implement channel transitions for tuya. disabled by default, and transition time and step are overridden to 2000 + 100. needs to be set to some value below the total time (i.e. `total transition time / step time == number of steps`, we need to figure out a correct time that serial comms could handle)
- lights custom provider (global, not per-pin) and state listeners
- remove lights code from relay module. implement through providers & listeners in the lights module, depend on RELAY_SUPPORT
- lights per-channel relay provider (unused atm), depend on RELAY_SUPPORT
- refactored channel transition - calculate step only once, make sure time + step values are sane, generate quick transitions with very small delay (10ms hardcoded) for transitions during OFF state i.e. we no longer waste 500ms (or whatever transition time is set to) on boot doing nothing
- transition time + step parameter for the lightUpdate
- report mask parameter for the lightUpdate
- minor fixes across the board

resolve #2222

- match paths through a custom AsyncWebHandler instead of using generic not-found fallback handler
- allow MQTT-like patterns when registering paths (`simple/path`, `path/+/something`, `path/#`)
Replaces `relay/0`, `relay/1` etc. with `relay/+`. Magnitudes are plain paths, but using `/+` in case there's more than 1 magnitude of the same type.
- restore `std::function` as callback container (no more single-byte arg nonsense). Still, limit to 1 type per handler type
- adds JSON handlers which will receive JsonObject root as both input and output. Same logic as plain - GET returns resource data, PUT updates it.
- breaking change to `apiAuthenticate(request)`, it no longer will do `request->send(403)` and expect this to be handled externally.
- allow `Api-Key` header containing the key, works for both GET & PUT plain requests. The only way to set apikey for JSON.
- add `ApiRequest::param` to retrieve both GET and PUT params (aka args), remove ApiBuffer
- remove `API_BUFFER_SIZE`. Allow custom form-data key=value pairs for requests, allow to send basic `String`.
- add `API_JSON_BUFFER_SIZE` for the JSON buffer (both input and output)
- `/apis` replaced with `/api/list`, no longer uses custom handler and is an `apiRegister` callback
- `/api/rpc` custom handler replaced with an `apiRegister` callback

WIP further down:
- no more `webLog` for API requests, unless `webAccessLog` / `WEB_ACCESS_LOG` is set to `1`. This also needs to happen to the other handlers. 
- migrate to ArduinoJson v6, since it become apparent it is actually a good upgrade :)
- actually make use of JSON endpoints more, right now it's just existing GET for sensors and relays
- fork ESPAsyncWebServer to cleanup path parsing and temporary objects attached to the request (also, fix things a lot of things based on PRs there...)

- 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

* experimental: refactor get/set/del/hasSetting

* sensors

* lights

* cleaup

* r

* tuya

* fixup! sensors

* fixup! tuya

* header defaults types

* fix lights

* setup already checks for max

* helper for flashstring

* fix overload

* oops

* refactor includes

* warnings

* test with migrate

* add ids in a separate file

* cleanup

rev: crash

rev: domoticz

rev: encoder

rev: loopdelay

rev: hass

rev: i2c

rev2: hass

rev: mqtt

rev: rfm69

rev: relay

rev: rpn

rev: settings setup

rev: hb settings

rev: telnet preprocessor fix

rev: settings wrap

rev: tspk bool style

rev: wifi types

rev: util hb

rev: settings

fixup! rev: settings

* rev: cleanup wifi injections based on new getters

* hasSetting now can return true for empty key

* show hardcoded network in web

* oops

* fix ws referencing wrong index

* ensure empty strings are written

* c/p

* use experimental schema style for payload, mark network as not deletable

* allow to customize converter

* shorter syntax, try using with wifi

* use proper #if syntax to handle definitions that are missing

* fixup ota sc checks getter, cast schEnabled to bool

* add utils header to sensors

* Update encoder

- import modified Encoder library
- customize minimum delta value

* minimum delta in header config

* fixup! minimum delta in header config

* fix dead code, actually use interrupts

* move static class methods to normal funcs, apply namespace

* drop hardcoded register use

- use peripheral api (see cores/esp8266/esp8266_peri.h)
- remove bitmask and register struct members

* add a note about changes

* fixup! add a note about changes