- 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