* light: fix inconsistent transitions

- capture step variable for the current transition
- use one-shot timer, restart from the timer callback

* schedule inside provider func, not transition

* web: re-add wifi scan action, send as json array

* ws: forcibly inline send functions

* Fix SSL check callback function definition

* Print secure client check as string

* use indexed getsetting
* store defaults in progmem

- customize relay TOGGLE payload
- match payload string when receiving mqtt status message
- reference enum values instead of raw integers, spell out intended status
- remove dead code

amend #1885, capitalize `relayPayload...` suffix instead of using uppercase
add `relayPayloadToggle`

- remove "platform" key, see #1440. this implicitly sets schema to "basic". pending some other clean-up regarding json and mqtt queueing, other schema can be added down the line 
- updated ws module queue elem to capture callbacks list, allows to pass more than one callback (for example, when they are generated on the fly as lambdas, see ha wsPost usage)
- modified method to send ha config to use global ws queue, fix #1762 problem with empty topics and ensure json allocation is consistent.
- use existing defines to set mqtt payload options. amend #1085, #1188, #1883 to use the set payload value. drop HOMEASSISTANT_PAYLOAD... defines. 
- update MQTT_STATUS_ONLINE/OFFLINE and RELAY_MQTT_ON/OFF with runtime configuration
- filter payload strings so that the resulting yaml value is not interpreted as bool (python True, False)
- helper method for settings to streamline string values manipulation

* Rework MQTT sync client configuration

* MQTT_LIBRARY_...

* comments

* fix not doing any checks for bearssl, remove afterconnected template for mqttclient

* comments

* comments

* secure bool stub

* typos, always include sc helpers

* fix on_fingerprint return type

* typo

* typo

* indent

* tag is already in config obj

* generate mqtt featureset string at compile time

* reword again

* trusted_root_ca

* test: etharp_gratuitous

* proper checks before calling etharp_gratuitous, move includes

* disable at runtime

* ms values

* reload

* debug

* reword

* filter by ifnum instead of checking for AP mode

* drop station_if check

2.3.0/lwip1 builds netif->num increments on for each sta or ap
lwip2 keeps those constant, but that seems like a implementation detail
might break in the future anyways...

* Stop updating SoftAP SSID and password when changing hostname and password via WebUI / settings `reload`:
https://gitter.im/tinkerman-cat/espurna?at=5d65418f49ac051923be1f06
* Show real ssid and psk values from the current sdk configuration instead of using getSetting
* `WIFI.STA` command

resolve #1763

* Light: proper printf format for HSV, use lround

* core: warn about map() and 2.3.0, type-strict constrain()

* use generic format

* value already has brightness

Fix Arduino IDE error by changing to proper relative paths:

```
In file included from sketch\config/all.h:36:0, from C:\Programy\arduino_projekty\espurna_dev\code\espurna\espurna.ino:22:
sketch\config/prototypes.h:178:86: fatal error: static/letsencrypt_isrgroot_pem.h: No such file or directory

#include "static/letsencrypt_isrgroot_pem.h" // Default to LetsEncrypt X3 certificate

compilation terminated.
```

* Use indexed keys for energy saving

* match else even when rtcmem cannot fit the value

* fix energy reset placement

* fix rtcmem->energy size check

* revert to pre 62a2b9e value, handle update from 1.13.5

* Syncronize js when saving important data

* update webui

* Add Shelly 2.5

* Add ADE7953 sensor support

* Fix compilation

* Use only one instance

* WIP: Not working, I got StoreProhibited exception

* Fix exception

* Fix merge issues

* Apply request review changes

* declare struct before using it

* uninterruptible delay

* try optimized reg_size

* fix types

* Remove gpio 0 input in analog sensor

* Add energy to ADE7953, it is not finished yet

* Add new method to save energy with index

* Finish energy for ADE7953

* MQTT rewrite with SSL fixes

- Added Arduino MQTT library support (actively maintained)
- Added support for BearSSL (core >= 2.5)
- BearSSL validation: insecure, fingerprinting and CA validation
- AxTLS validation: insecure and fingerprinting
- Support MFLN in order to reduce heap usage

* Better header incl, fix building w/ no NTP_SUPPORT

* Clean up code, use DEBUG_MSG_P

* Fix compile error

Thanks to @tonilopezmr 
1c3d68af34

* clean-up ws declarations, remove old stubs

* always fw declare callback types

* wsPost is only possible with WEB_SUPPORT

* some more ws methods

* Core 2.6.0+ fixes

* fix env -> config, run travis04 job

* don't duplicate free heap in frag data, use single stats struct

* fix dtostrf warnings, bump buffer sizes

* ...and even less words for fragmentation stat