core cpu: add defaulttransceiver pseudomodule

update examples/default
make: add Makefile.pseudomodules and use it

BASELIBS now defines targets for anything in USEMODULE that is not in PSEUDOMODULES
move defaulttransceiver to Makefile.pseudomodules
tests/test_net_if: use defaulttransceiver
tests/test_net_if: update BLACKLIST/WHITELIST
tests/test_pnet: use defaulttransceiver
examples: make includes adhere to coding conventions
Merge pull request #912 from mehlis/fix-includes

examples: make includes adhere to coding conventions
Merge pull request #609 from LudwigOrtmann/transceiver_any

anytransceiver pseudomodule
Fix test_pnet