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