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/.

Make include dependencies neater, and adheres to the coding convention
that headers should not include headers.

This does not affect code size or performance when debugging turned off.

To address issue #420.

Adds readline_init() to clear readline history on soft reset.  Addresses
issue #387.