cpu/stm32f0: fixed hardfault indication
prevent rounding 0 if HWTIMER_SPEED > 1000000L

The current macros in hwtimer.h expect HWTIMER_SPEED to be < 1000000L, otherwise integer arithmetic will round the result down to 0.
Add a case to prevent that.
cpu/stm32f4 changed SPI-return values to API defs
sys/transceiver: cc2420 handles 802.15.4 packets
shell/transceiver: properly initialize 802.15.4 packet
cpu/cc2538: centralized all cpu specific includes

- added all CPU specific includes to cpu-conf.h
- removed now not needed includes from cpu .c files
doc: some doxygen cleanups

* removed RIOT unrelated cpu documentation
* introduced cpu_specific prefix to mark such documentation
* put oneway_malloc and crypto into sys group
doc: updated doxygen configuration

Updated with `doxygen -u`
doc: fix documentation for hwtimer

@verbatim was used incorrectly and a closing html tag was missing
cpu: use typed function pointer for thread_arch_init
doc: fixed remaining doxygen warnings in core

Only one warning remains and will be fixed in a separate commit.
Merge pull request #1866 from OlegHahm/core_fix_thread_init_prototype

cpu: use typed function pointer for thread_arch_init
cppcheck: don't needlessly assign sched_active_pid
Add copyright information to lpc1768/include/cpu.h
doc: exclude more CPU specific stuff from doxygen
doc: fix doxygen warnings for color module

Also fixes the module name in API documentation.
doc: fix ambiguous file name warnings

doxygen does a good job itself, identifying the unique part of the path
to identify a file.
doc: fix naming for Cortex M3 common group
doc: put atmega cpu file into the right group
doc: fix vtimer documentation