unittests: Force execution of $(UNITTEST_LIBS) build target
core:debug: documentation for `DEBUG_PRINT` was confusing and wrong
native: fix coding style
native: set optional path with unix socket option

fixes #1045
Merge pull request #1214 from LudwigOrtmann/issue-1045

native: unix socket path enhancement
Merge pull request #1238 from authmillenon/makefile-unittests

unittests: Force execution of $(UNITTEST_LIBS) build target
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