5.7.0

• New boards:
  • AfroFlight Rev5 (8MHz)
  • BlackPill F401CC
  • Core board F401RCT6
  • MKR Sharky
  • Nucleo G431KB
  • Nucleo G431RB
  • Nucleo G474RE
  • RHF76 052
  • SensorTile.box
• Updated mbed framework to 5.14 (release notes)
• Updated support for Arduino framework 1.7.0 (release notes) (issues #253, #291)
• Enabled mbed framework for Nucleo H743ZI (issues #279, #280)
• Enabled cmsis framework to STM32F446ZE (issue #297)
• Fixed custom target example, system_clock.c is now common for L4 targets
• Fixed memory size for genericSTM32F103T8 board
• Fixed upload process via serial protocol (issue #269)