added NORETURNs to functions that should not return
and added `UNREACHABLE();` to hint the compiler unreachable lines

added right signature for first parameter of `thread_stack_init()`
added `UNREACHABLE();` macro to `cpu/lpc1768/atom.c` and `cpu/msp430-common/cpu.c`
Exclude *.c files from make doc
Exterminate old-style function definitions
Exterminate old-style function declaration/prototypes
make: add own file for CFLAGS feature tests
make: fast out on old-style function definitions
sys:crypto: put ciphers into one module
Add process indicator to compile_test.py
fix license to LGPL

fixes #1155 needs @haukepetersen to review
unittests: exit(1) or error
added missing Licence in at86rf231 driver files.
Merge pull request #1162 from AlaeddineWeslati/master

added missing Licence in at86rf231 driver files.
Merge pull request #1159 from thomaseichinger/fix_license_sam3x8e

sam3x8e: fix license to LGPL
Merge pull request #1161 from Kijewski/unittests-exit-code

unittests: exit(1) or error
unittests: use subfolders for different tests

Unittests for e.g. different libraries can be put into
`tests/unittests/tests-XXX`, where `XXX` is your test suite.

If `unittests` is made with `make all` (or any explicit argument), then
all test suites get built. If you use `make tests-XXX tests-YYY …` then
only the test suites `XXX` and `YYY` get built.
Merge pull request #1164 from Kijewski/unittests-use-subfolders

unittests: use subfolders for different tests
unittests: separate test suites from main.c

This change removes the need to patch the main.c if you add or remove a
test suite. A test suite in `tests/unittests/tests-XXX` needs to export
the function `void tests_XXX(void)`, which gets called by `main()`.

The `tests-XXX/Makefile` looks like your average module:
```
MODULE = tests-XXX
include $(RIOTBASE)/Makefile.base
```
Merge pull request #1124 from Kijewski/consolidate-crypto

sys:crypto: put ciphers into one module
Merge pull request #1119 from Kijewski/error_old-style-definition

Exterminate old-style function definitions
sys/crypo: fix function declarations

In #1119 old-style function declarations are exterminated and forbidden.
I missed the functions in `sys/crypto` because they weren't used
throughout the tests/examples before #1124.