Rename guhRF platform to osd-merkur-256, previous osd-merkur platform is
now osd-merkur-128. Also check that everything is consistent.
Add both platforms to the regression tests.
Move redundant files in platform dev directory of both platforms to
cpu/avr/dev. Note that this probably needs some rework. Already
discovered some inconsistency in io definitions of both devices in the
avr/io.h includes. Added a workaround in the obvious cases.
The platform makefiles now set correct parameters for bootloader and for
reading mac-address from flash memory.
Factor the flash programming into cpu/avr and platform/osd-merkur* and
rework *all* osd example makefiles to use the new settings. Also update
all the flash.sh and run.sh to use the new settings.
The suli ledstrip modules (and osd example) have also been removed.
