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

Make pyboard.enter_raw_repl more robust

py: Use <alloca.h> for alloca()

mingw: Add 'open' as extra builtin

Ignore .exe files

Well, it is bound to "detailed error reporting", but that's closest what we
have now without creating new entities.

This one was probable missed when creating mpconfigport.h, but the underlying
code (file.c) gets compiled and works perfectly so no reason to omit it.

alloca() is declared in alloca.h which als happens to be included by stdlib.h.
On mingw however it resides in malloc.h only.
So if we include alloca.h directly, and add an alloca.h for mingw in it's port
directory we can get rid of the mingw-specific define to include malloc.h
and the other ports are happy as well.

Fix PB0 ADC typo.

Add device ID to autoflash script.

Fix pyboard.py tests.

This also adds a bunch of slashes separating pin that have multiple functions.

Specifically, nlr.h does.

TODO: Rename methods.

This is ugly, just as expected.

Fix pin initialization when a mode argument is provided

Add flashboard target to the stmhal Makefile to run dfu-util

Fix the builtin min() and max() functions (and add tests).

Fixes #539

In case there's a program in the microcontroller's main.py running in an infinite loop