core: only store the stack size for DEVELHELP

`tcp_t::stack_size` is only examined by the shell command `ps` and
`DEBUG_PRINT`. For the latter one only if `DEVELHELP` was enabled.

This PR guards the member `tcp_t::stack_size` in `#ifdef DEVELHELP`.
Only if DEVELHELP was activated its value get printed by `ps`.

Closes #1287.
core: thread_measure_stack_free() is only useful for DEVELHELP
sys/transceiver: make transceiver_pid volatile

- because it is
SQUASHME: clean out extern kernel_pid_t transceiver_pid redefinitions
tests, native: fixup for cpuid

- adopt test name to new scheme
- make cppcheck happy / dont overwrite the target memory location twice
- fix license header
- don't redefine define if it already exists
- don't write more cpuid than is defined as size
tests: fix cppcheck findings

- bitarithm_timings: use more void, decrease range
- struct_tm_utility: add cppcheck-suppress invalidscanf
core/queue: queue -> priority_queue

Rename queue to priority queue, because that's what it is.
core/priority_queue: add dynamic initializers

- priority_queue_init
- priority_queue_node_init
Merge pull request #1527 from LudwigOrtmann/cppcheck-tests

tests: fix cppcheck findings
Merge pull request #1534 from LudwigOrtmann/queue-cleanup-two

core/queue: queue -> priority_queue && dynamic initializers
cpu/cortex-mX_common: bugfix to arch_stack_init

- fixed cortex-[m0|m3|m4]
Merge pull request #1529 from LudwigOrtmann/cpuid_fixup

tests, native: fixup for cpuid
doc: fix flashrom doxygen
boards/cpu: fix some warnings
Merge pull request #1293 from Kijewski/issue-1287

core: only store the stack size for DEVELHELP (implementation)
Merge pull request #1547 from haukepetersen/fix_cortex_threadarch

cpu/cortex-mX_common: bugfix to arch_stack_init
"tests": print tcb_t size

The "test" should aid #303.
Merge pull request #1525 from LudwigOrtmann/morning-cleanup

doc, boards/cpu: cleanup
Merge pull request #1535 from LudwigOrtmann/transceiver_volatile

sys/transceiver: make transceiver_pid volatile
cbor: CBOR implementation for RIOT-OS

This is a malloc-free implementation of the Concise Binary Object
Representation (CBOR) data format for the RIOT-OS.

This implementation mostly stand-alone, and it should be pretty easy to
port to other platforms. We're only using the C STL and some custom
network-related functionaliy which could be easily replaced by depending
on arpa/inet.h.

The CBOR API is straight-forward to use and provides encoding/decoding
functionality for all major C types, such as:
- int
- uint64_t
- int64_t
- float
- double
- char*
- struct tm
- time_t

It is possible to conditionally compile this module via CFLAGS:
- CBOR_NO_SEMANTIC_TAGGING: All semantic-tagging features removed
- CBOR_NO_CTIME: All ctime related features removed
- CBOR_NO_FLOAT: All floating-point related features removed
- CBOR_NO_PRINT: All features depending on printf removed