Initialize RTC period coefficients, etc. if RTC RAM doesn't contain valid
values. time.time() then will return number of seconds since power-on, unless
set to different timebase.
This reuses MEM_MAGIC for the purpose beyond its initial purpose (but the whole
modpybrtc.c need to be eventually reworked completely anyway).
The first argument to the type.make_new method is naturally a uPy type,
and all uses of this argument cast it directly to a pointer to a type
structure. So it makes sense to just have it a pointer to a type from
the very beginning (and a const pointer at that). This patch makes
such a change, and removes all unnecessary casting to/from mp_obj_t.
py/mphal.h contains declarations for generic mp_hal_XXX functions, such
as stdio and delay/ticks, which ports should provide definitions for. A
port will also provide mphalport.h with further HAL declarations.
Paul Sokolovsky