core/hwtimer: disable interrupts in hwtimer_remove

Before only the hardware timer's own interrupt was being disabled.
This led to a race condition in the following scenario:

```
Thread1:
    hwtimer_remove()
    hwtimer_arch_disable_interrupt();

// INTERRUPT -> Thread2 (which has a higher priority than Thread1) gets scheduled

Thread2:
    ...
    hwtimer_remove()
    hwtimer_arch_disable_interrupt(); // hwtimer interrupt is already disabled
    ...
    hwtimer_arch_enable_interrupt();
    ...
   // yield | terminate -> Thread1 gets scheduled again

Thread1:
    ... // these instructions are being run with the hwtimer interrupt enabled
    hwtimer_arch_enable_interrupt(); // hwtimer interrupt is already enabled
```

Fixes #924
documentation: fix doxygen for `pthread_*.h`

The pthread header files aren't in the doxygen page anymore after #1137,
because I `@file`'d the `.c` files, not the `.h` files.

This change moves doxygen boilerplate.

Closes #1199.
native: set _native_pid correctly in daemon mode

This fixes a bug that leads to all unix sockets being created as
`/tmp/riot.tty.0`.
Merge pull request #1216 from LudwigOrtmann/issue-1215

native: set _native_pid correctly in daemon mode
Merge pull request #1208 from Kijewski/issue-1199

documentation: fix doxygen for `pthread_*.h`
core: kernel: improved doxygen documentation

also added param[in] to irq.h and fix order of doxygen endguards
Merge pull request #977 from mehlis/doxygen-irq

core: kernel: improved doxygen documentation
Merge pull request #1193 from LudwigOrtmann/issue-924

core/hwtimer: disable interrupts in hwtimer_remove
msp430: provide oneway-malloc implicitly

For MSP430 boards oneway-malloc is already used *if* `malloc.h` was
included. The problem is that `malloc.h` is not a standard header, even
though it is common. `stdlib.h` in the right place to look for
`malloc()` and friends.

This change removes this discrepancy. `malloc()` is just named like
that, without the leading underscore. The symbols now are weak, which
means that they won't override library functions if MSP's standard
library will provide these functions at some point. (Unlikely, since
using `malloc()` on tiny systems is less then optimal ...)

Closes #1061 and #863.
Add doxygen comments to MSP's oneway malloc
msp/tests: remove blacklist from test_bloom_bytes

Issue #1061 was fixed.