[platform/native] Add to doxygen tree
[doc/cpu.txt] added pic32 and aducrf101 cpu
[doc/html/img/esb] deleted obsolete folder
[cpu] removed faulty group names
[doc/html] Removed .cvsignore
[cpu/arm] removed free-standing @addtogroup command
[doc] Fixed and simplified doc/cpu.txt
[cpu/arm] Added doxygen .txt files for gaining a minimum of documentation structure
[cpu/pic32] Removed excess end group
[cpu/stm32w108] Doxygen grouping and group name fixes
[doc] Memory functions should be listed under 'Libraries'
[doc] Added minimal doxygen anchor for each platform currently available in Contiki

Already existing label names and titles were retained
[doc] avr-atmega128rfa1: add to parent platform group
[doc] llsec moved in net group
[doc] avr-raven: Fix placement of description for ravenserial group

Note: The raven-lcd-interface and raven-ipso modules in atmega128rfa1
seem to be needles for this platform and might be there only because of
copy&paste from the raven platform. Should be removed in a later patch.
[doc] Give files a common structure by placing license first (partial)

Followed by doxyen file and group tags.
This patch is only a first attempt to make provide a clean structure,
many more files require rework, too.