Allow defining a specific rom length to use for linking the firmware,
_fw_rom_length, instead of the default configuration to use the whole rom from
_rom_offset to the end.
* Add cortexm_common/Makefile.include FW_ROM_SIZE configuration
* Add an assertion that _fw_rom_length still respects _rom_length
Define _rom_offset with a conditional evaluated at execution time to allow
setting it in compilation rules and generate in the same make instance different
elf files with different configurations.
- removed coretx-m[0|3|4]
- moved their content to cortexm_common
- adjusted cortex Makefiles to this new name
- adjusted cortex Makefiles new structure
- fixes to cortexm-common
- Added ARM CMSIS headers to cortexm_common
- thread_exit fixes to cortexm-common
- cortexm-common adjusted documentation
- cortexm_common added eINT dINT defines for now
