[GENLINK] Add examples of use to STM32 directories
[GENLNK] Update submodule to use my branch
[BUILD] Modified makefiles for better detection of the library path

it can be overriden in the particular example project by writing:

make all SRCLIBDIR=/path/to/libopencm3/directory

The autodetection searches for sublime project, because *.a files may be deleted in the CLEAN target.