amendment - to be squashed
Fixup for #685

- use DEVELHELP for native as well
- fix function name in documentation
- improve documentation language/spelling
adding sys/time.h for msp-430
Don't build PKGs twice
Merge pull request #800 from OlegHahm/msp430_sys_time

cpu: msp430-common: adding sys/time.h for msp-430
make: couple include path and -I

This is necessary if includes have to be filtered, such as in native
to throw out RIOTs posix includes which interfere with system
includes.
Merge pull request #803 from LudwigOrtmann/couple_include_defs

make: couple include path and -I
Don't use INCLUDES for building any native at all.

native modules will never need the dynamic INCLUDES, so we define our
own NATIVEINCLUDES. Due to the current make structure, the only way to
not use INCLUDES is to redefine the build rules.
native/posix: Don't include sys/types.h in sem

`sys/types.h` contains the native definition for `pthread_*_t`. This
causes clashes if you want to use `semaphore` and `pthread` in the same
application.
examples: fix rpl_udp README regarding invocation
Merge pull request #807 from LudwigOrtmann/examples_rpl_udp

examples: fix rpl_udp README regarding invocation
Include kernel.h for inet_pton for MSP-430
Merge pull request #790 from LudwigOrtmann/fixup_685

core: fixup for 685
Merge pull request #808 from authmillenon/inet_pton_msp_430_fix

Include kernel.h for inet_pton for MSP-430
Fix coding conventions in sys/transceiver/transceiver.c
tests: add test that shows sequence of received messages
test_thread_msg_seq: add missing main() return statement
tests: test_shell: call "make term" instead of hardcoded pseudoterm
Merge pull request #819 from kaspar030/tests_fix_shell_tests

tests: test_shell: call "make term" instead of hardcoded pseudoterm
Add automatized test for sha256