BPP

Dear raising IOTlers,

as already discussed in https://github.com/RIOT-OS/RIOT/issues/2851, I finally initiated a first version of RIOT's Best Programming Practises (BPP) in the wiki at https://github.com/RIOT-OS/RIOT/wiki/Best-Practice-for-RIOT-Programming

Feel free to improve and extend!

Cheers, Oleg