Moved AnotherMixCompiler from examples to tests, corrected tab character in source code
renamed AnotherMixCompiler to test_another_mix_compiler, pull BytesGalore's PR #770
corrected makefile name
removed unnecessary parts in test_cpp_mix/Makefile to keep things simple
added NOTE to test_cpp_mix/README.md
added export var RIOTCPU and RIOTBOARD to use with iot-lab_M3