[STM32xxx] CoIDE exporter and gcc_arm ...

- 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 per default but now
it is the same as in linker script)
- gcc linker script: changed the memory size from hex number e.g. 0x2000
to decimal 8K

[NUCLEO_L152RE] exporters for gcc_arm and coide