makeqstrdata: print error to stderr.
py: Wrap mpz float functions in MICROPY_ENABLE_FLOAT.
Merge branch 'master' of github.com:micropython/micropython
Implement ROMable modules.  Add math module.

mp_module_obj_t can now be put in ROM.

Configuration of float type is now similar to longint: can now choose
none, float or double as the implementation.

math module has basic math functions.  For STM port, these are not yet
implemented (they are just stub functions).