core: sched: thread: optimize thread status field usage

see PR #716 for discussion
sys: update ps to reflect thread status variable changes
Changes to `thread_wakeup`

`thread_wakeup` did not check if target pid is invalid.

`thread_wakeup` used `dINT` and `eINT` directly.
It should use `disableIRQ` and `restoreIRQ` instead, because there might
be other (good) reasons why one might want to call `thread_wakeup` with
interrupts disabled.

`thread_wakeup` yielded even if the other thread had a lower priority
than the current thread.
Allow escaped characters in shell

Per #708.

This patch allows escaped characters in the shell, and makes the
apostrophe a quotation mark. The escape character is backslash.

The term "escape character" is used liberally in here: if a backslash is
encountered in the command line, the next character will be taken
verbatim. No escape sequences are understood, i.e. `"\n"` is just the
letter `n`, not a new line.
Fixup for #685

- use DEVELHELP for native as well
- fix function name in documentation
- improve documentation language/spelling
Don't build PKGs twice
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: 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
Allow IEEE 802.15.4 addressing types for transceiver

IEEE 802.15.4 has two addressing modes: 16-bit short and the device's
EUI-64. Currently RIOT supports only sending of packets with 16-bit
short addresses via the transceiver interface. This patch allows at
least for the radio chips that support IEEE 802.15.4 to let the
application/upper layer decide which addressing mode to use.

Upper layer implementation will be implemented in follow-up PR to #460