Release mega-20190823

Changes in mega-20190823 (since mega-20190817):

Bartlomiej Zimon (4):
      [Modbus RTU] drop all data in buffers
      [Modbus RTU] do more checks with received packet
      [Modbus RTU] one more buffer check
      [Modbus RTU] add slave number check

ESPEasy release bot (1):
      automatically updated release notes for mega-20190823

Gijs Noorlander (9):
      Rename _P115_HeatpumpIR.ino to _P088_HeatpumpIR.ino
      Wrap P088 in USES_P088 defines
      Fix Build issues P088_HeatpumpIR
      [Heatpump IR] Add minimal IR_ext build for 4M flash nodes
      [PlatformIO] Move duplicate lines to global [env]
      [PlatformIO]  Maintain same order of platform and build_flags
      [PlatformIO] Fix missing define on some core 2.4.x builds
      Remove test_core_260_sdk2_alpha builds
      [Build] Remove all core 2.6.0 SDK2 builds

Toni (4):
      Add HeatpumpIR 1.0.9 library
      Add HeatpumpIR plugin P115
      Fix compile warnings in HeatpumpIR plugin
      Configurable MQTT package size in Controller.ino