To be consistent with MP_UNARY_OP_INT_FLOAT and MP_UNARY_OP_INT_COMPLEX,
and allow int() to first check if a type supports __int__ before trying
other things (as per CPython).
Signed-off-by: Damien George <damien@micropython.org>
This is consistent with the other 'micro' modules and allows implementing
additional features in Python via e.g. micropython-lib's sys.
Note this is a breaking change (not backwards compatible) for ports which
do not enable weak links, as "import sys" must now be replaced with
"import usys".
Tests which don't work with small ints are suffixed with _intbig.py. Some
of these may still work with long long ints and need to be reclassified
later.
