Blanket wide to all .c and .h files.  Some files originating from ST are
difficult to deal with (license wise) so it was left out of those.

Also merged modpyb.h, modos.h, modstm.h and modtime.h in stmhal/.

New way uses slightly less ROM and RAM, should be slightly faster, and,
most importantly, allows to catch the error "non-keyword arg following
keyword arg".

Addresses issue #466.