core:debug: documentation for `DEBUG_PRINT` was confusing and wrong
x86: fix download script for OSX

Mac OSX does not have `wget`, but `curl`.
It does not understand `tar xJ`, but `tar xj`.
Merge pull request #1250 from Kijewski/x86-osx-fix-download

x86: fix download script for OSX
Merge pull request #1248 from thomaseichinger/debug_h_doc_fix

core:debug: documentation for `DEBUG_PRINT` was confusing and wrong
destiny: segfault due to dereferencing nullpointer
get_socket(i) returns NULL, when no specific socket is found.
Without an appropriate check for NULL, the current state
of the code leads to a segfault.

destiny: added parens

destiny: continuing the loop makes more sense than returning at first sight of NULL
Merge pull request #1269 from cgundogan/fix_get_waiting_connection_socket_null_check

destiny: segfault due to dereferencing nullpointer
core: fix variable name for sched_pidlist
Merge pull request #1272 from OlegHahm/sched_pidlist_fix

core: fix variable name for sched_pidlist
vtimer: fix callback usage

There is no need to test the "handler" set in the vtimer struct, and
have some code executed then. We just can make the code to execute the
handler. To lengthy `if else if`, just a call.
vtimer: fix vtimer_remove()
vtimer: minor style fixes
vtimer: unify and enhance interface

Currently the vtimer only accepts relative timestamps, even though it
uses absolute timestamps internally. This PR adds the parameter
`vtimer_absolute_t absolute` to every function, which is either
`VTIMER_RELATIVE` or `VTIMER_ABSOLUTE`.

`vtimer_sleep()` sleep uses `thread_sleep()` now instead of
`mutex_lock()` to allow spurious wake ups. A parameter `int *spurious`
is added, which is set to 0 if the wake up was not spurious.
vtimer: split .c file for clearity