* 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

- 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

* enable multiple Digital, Events & PulseMeter

* delete SPI dependency

* back to only one PulseMeter

* deprecared pins

- 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

* PZEM004T: runtime port and address settings

* Add nodemcu-pzem004t test env

* pzEneTotal -> pzemEneTotal

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

This change adds a second sensor object to deal with two sensors, if BMX280_NUMBER == 2

* send all ws config at once on start
* reduce ws json overhead by creating message buffer manually
* use k:[values] instead of k1:value1, k2:value2 etc. for lists

This reverts commit 7ad0e3a02b.

* Fix energy ratio input for pulse meter sensor

* checkout origin/dev -- webui files

* Testing branch

* Added ability (by define) to scale analog sensor, also with number of decimals (it was formerly zero)
Useful when running on batteries to check the battery voltage just 
adding the appropriate resistor

* Reverting DHTSensor.h file

* Trying again to revert DHTSensor.h

* Using macro DEBUG_MSG

* fix method types

* Testing branch

* Added ability (by define) to scale analog sensor, also with number of decimals (it was formerly zero)
Useful when running on batteries to check the battery voltage just 
adding the appropriate resistor

* Reverting DHTSensor.h file

* Trying again to revert DHTSensor.h

* Using macro DEBUG_MSG

* fix method types

* Works with many different ultrasonic sensor models: HC-SR04, SRF05,
  SRF06, DYP-ME007, JSN-SR04T & Parallax PING)))™.
* Built-in digital filter method ping_median() for easy error correction
  (use SONAR_ITERATIONS build flag to configure).
* Allows setting of a maximum distance where pings beyond that distance
  are read as no ping or clear (use SONAR_MAX_DISTANCE build flag).

Add button definitions to the travis02 and travis03
IR_BUTTON should be uint32_t to properly work with new macro
eepromRotate return value is not used