fixed printf formatter
redefining default stack sizes dependent on the use of printf
allow external modules to be added to a project
added missing include to cc110x_ng
some buffer adjustments
Revert "removed redefined ENABLE_DEBUG"

This reverts commit 69c526f44dedffe1118ba90ea418c8cb342cf46b.

Instead of removing ENABLE_DEBUG, define it as zero and replacing the
ifdef preprocessor commands by a simple #if
fixed some includes
add typedefs to socket.h to improve POSIX compliance
Merge pull request #76 from benpicco/posix_compat

add typedefs to socket.h to improve POSIX compatibility
Merge pull request #75 from benpicco/external_modules

Allow external modules to be added to a RIOT project