* debug: heap fragmentation stat

* Rework method detection

- return check integral type as a result of detection instead of method type
- type-tagging instead of enable_if

* fix alias

* typo

* only need one bool_type instance

* Move heap debug into HeapStats header

- don't show fragmentation stats on the first call
- prettify fragmentation display
- pack function params into helper struct
- naming

* pass external flag instead

* add missing prototypes

Fix PSH environments

Disable Serial log for hardware using TX or RX pins

MQTT connection state

Rename NTC/LDR_SENSOR to NTC/LDR_SUPPORT

* Added new core versions 2.5.1/2.5.2 with matching PlatformIO versions

* Update platformio.ini

* add CCT support for 2 channel boards

* update webinterface description

* add 2 channel CCT to homeassistant and domoticz

* remove domoticz two channel cct support.

* MQTT: config change detection
* Reload settings when config json is uploaded
* Apply only new settings
* Finish config early when not enabled
* Reuse existing buffers from getSetting String using std::move

* MQTT and HA brightness shall only be depended on LIGHT_PROVIDER != LIGHT_PROVIDER_NONE

* remove unnecessary changes

Allow defining custom device name for alexa integration, other than hostname.
Still uses hostname as a fallback.

- store system crash counter and reset reason in rtcmem instead of eeprom
- store relay state mask in rtc in addition to the eeprom
- store relay state in eeprom only when boot mode requires it
- simplify relay state mask calculation / reading using std::bitset
- light state save and restore
- energy total save and restore

- remove optional RFRAW_SUPPORT
- enable module when RF_SUPPORT=1, optionally enable RCSwitch
- reorder ifdef checks to treat RFB_DIRECT and old RF_SUPPORT the same
- rename RF_PIN to RFB_RX_PIN
- depend on RF_SUPPORT instead of ITEAD_SONOFF_RFBRIDGE
- runtime TX & RX PIN setting

* Add "Enable Thermostat" switch

* Add heater/cooler thermostat mode

* PZEM004T: runtime port and address settings

* Add nodemcu-pzem004t test env

* pzEneTotal -> pzemEneTotal

Removed in favour of BW-SHPX bin

https://github.com/xoseperez/espurna/issues/1465#issuecomment-484566975

* Call delay() after callbacks
* Use safer loop delay value

Update CHANGELOG.md

One line duplicated

Update BMX280Sensor

- dynamic number and address setting
- do not return i2c-specific error for wrong values

Send RF MQTT message with retain off