Build GNU environment for stm32 development

• OS
  Ubuntu 18.04 LTS

• Toolchain
  https://github.com/gnu-mcu-eclipse/arm-none-eabi-gcc/releases

• IDE
  GNU MCU Eclipse - includes the latest Eclipse CDT and the latest plug-ins
  https://github.com/gnu-mcu-eclipse/org.eclipse.epp.packages/releases

• adapter
  openjtag/jlink

• debugger
  https://github.com/gnu-mcu-eclipse/openocd/releases