remove .cpp from the resulting suffix, since .ipp already implies it is c++
update comments once again

fixes #2479

- provide a queue for the outgoing messages, don't depend on the MQTT
  callback implementation details and always postpone the actual transfer.
- generate user input parsers using re2c, adds special PlatformIO build handlers
- add terminal command to show GPIO info and send a simple payload
- rework button<->action presets into value<->terminal command presets and custom ones
  through the use of `irCmd<VALUE>` settings, where the VALUE is taken from the simple payload
  (yet, it does not understand repeated codes, but that's something to add later *or* use rpnlib)
- add tx message integration for the relay module via `irRelayOn#` and `irRelayOff#`
- rework simple payload to include 'repeats' value for the 'IRsend::send()'
  also adds internal 'series', 'delay' and includes full 64bit 'value'
  (as uppercase HEX, instead of decimal)
- rework raw payload to use 'series' instead of 'repeats', and provide a
  clear distinction between the usec time and the options of the message
  by moving the required options to the front and separating them using ':'
  (just like the simple variant)
- make RX and TX pin a runtime setting, make RX and TX support a build flag
- small test framework to check whether internal string encode<->decode works

Also updates the hexEncode & hexDecode implementations to use
'iterators' instead of just pointer + index.

Garland merge updated .gitattributes, fixup the difference before
merging anything else :>

Port of https://github.com/Vasil-Pahomov/ArWs2812 from Arduino to ESP8266
Implementing garland of WS2812

Co-authored-by: Dmitry Blinov <dblinov@blackberry.com>