This can be generalised if/when more processing is needed by SysTick.

Thanks to @chuckbook for the idea.

- add mp_int_t/mp_uint_t typedefs in mpconfigport.h
- fix integer suffixes/formatting in mpconfig.h and mpz.h
- use MICROPY_NLR_SETJMP=1 in Makefile since the current nlrx64.S
  implementation causes segfaults in gc_free()
- update README

The BSD stuff is a copy from the unix makefile but at least there it
makes some sense, a windows makefile on BSD doesn't.
The -lmman flag is probably for mmap functions but there is no other build
support for it on windows so just that flag won't cut it anyway.

This started out using IgorLektorovEpam work in PR #1389
and reworked it.

Turning on each DMA block increases the current consumption
by about 8 mA. This code adds an idle timer for each DMA
block and turns off the clocks when no streams are in use
for 128 msec. Having a small timeout allows for improved
performance when back-to-back transfers are being performed.

The 128 msec is basically a guess.

- added some comments to explain the priority/sub-priority.
- adds an entry for SDIO (to be used in a later patch)
- increases DMA priority above USB so that DMA can be used
  for sdcard I/O when using USB Mass Storage.

If RTC is already running at boot then it's left alone.  Otherwise, RTC is
started at boot but startup function returns straight away.  RTC startup
is then finished the first time it is used.  Fallback to LSI if LSE fails
to start in a certain time.

Also included:
 MICROPY_HW_CLK_LAST_FREQ
        hold pyb.freq() parameters in RTC backup reg
 MICROPY_HW_RTC_USE_US
        option to present datetime sub-seconds in microseconds
 MICROPY_HW_RTC_USE_CALOUT
        option to enable RTC calibration output

CLK_LAST_FREQ and RTC_USE_CALOUT are enabled for PYBv1.0.

This patch checks that there is only one *, and that ** is last in the
arg list.

Fixes issue #1623.

Loading .mpy files will now check to make sure that the target VM can
support the bytecode.

Tested by comparability to small int/casting to bool.

And thus can be successfully used in comparisons, etc.

%f prints true integer digit, so its calculation should happen before any
exponential scaling.

This takes previous IEEE-754 single precision float implementation, and
converts it to fully portable parametrizable implementation using C99
functions like signbit(), isnan(), isinf(). As long as those functions
are available (they can be defined in adhoc manner of course), and
compiler can perform standard arithmetic and comparison operations on a
float type, this implementation will work with any underlying float type
(including types whose mantissa is larger than available intergral integer
type).

In other words, unix port now uses overriden printf(), instead of using
libc's. This should remove almost all dependency on libc stdio (which
is bloated).

This may not seem like the ideal place, but is actually the only place
in py/ where it gets referenced, so is just right.

Return tuple of (address_family, net_addr, [port, [extra_data]]). net_addr
is still raw network address as bytes object, but suitable for passing to
inet_ntop() function. At the very least, sockaddr() will separate address
family value from binary socket address (and currently, only AF_INET family
is decoded).