[STM32xxx] CoIDE/gcc_arm exporter and startup_stm32xx update

Several updates/additions of missing functions/corrections:

- CoIDE options: wrap main and linker option DiscradUnusedSection=1 was missing in some targets
- CoIDE options: corrected flash loader config for Nucleo_F030 and Nucleo_F072
- CoIDE options: corrected memory layout (not used by default but now they are the same as in linker scripts)
- some gcc linker scripts: changed the memory size from hex number e.g. 0x2000 to decimal e.g. 8K

- startup files: updateing to current versions of STM32 Cube drivers, original files without any changes:
- DISCO_F303VC
- DISCO_F334
- NUCLEO_F030
- NUCLEO_F072
- NUCLEO_F302
- NUCLEO_F334

- a missing wrap main in gcc_arm template of DISCO_F303 target