make native includes RIOT posix compatible
further clean up / filtering for cpu
fix nativenet_send documentation
make buildtest output coloured
change astylerc for astyle 2.0.4

brackets=attach becomes attach-namespaces
Change to 1tbs in .astylerc

adds backwards compatibility
addresses https://github.com/RIOT-OS/RIOT/pull/475#issuecomment-31639014
mute build tools (to be consistent with the rest of the build system)
build everything in the project directory
move include directives from header to C file
simplify and unify include pathes

additional:
* exporting include path in sys is mandatory for subfolders
* removed duplicate object file in linker call
correct filename
simplify include structure for boards

* do not overwrite CFLAGS in boards Makefile
simplified and unified cpu build structure
removed redundant include pathes from Makefiles
removed superfluous slash after BINDIR
further Makefile cleanup
use proper variables in board Makefiles
create BOARDS subdirectory for binaries
muting compiler and binutils optionally

Instead of muting all compiler and other binutils output by default,
introduce a variable to make this behaviour configurable.
add basic include pathes by default