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/.

Convert int types to uint where sensible, and then to uint8_t or
uint16_t where possible to reduce RAM usage.

Also add command line option to unix port to select emitter.

Byte code has a map from byte-code offset to source-code line number,
used to give better error messages.

A big change.  Micro Python objects are allocated as individual structs
with the first element being a pointer to the type information (which
is itself an object).  This scheme follows CPython.  Much more flexible,
not necessarily slower, uses same heap memory, and can allocate objects
statically.

Also change name prefix, from py_ to mp_ (mp for Micro Python).