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
ringbuffer: remove example
ringbuffer: add convenience functions

This patch add `peek` functionality, and empty and full helpers.
ringbuffer: fix parameter types

It is a bad idea to use signed types for lengths.
Mark pointers a `restrict`, since the ringbuffer is not thread safe
anyway.
ringbuffer: remove pointer to the end

There is no need for an explicit pointer to the end of the buffer.
ringbuffer: don't overwrite in `ringbuffer_add`
ringbuffer: add documentation
ringbuffer: add static initializer
ringbuffer: add test for add_one and get_one