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This patch changes how most of the plain math functions are implemented:
there are now two generic math wrapper functions that take a pointer to a
math function (like sin, cos) and perform the necessary conversion to and
from MicroPython types.  This helps to reduce code size.  The generic
functions can also check for math domain errors in a generic way, by
testing if the result is NaN or infinity combined with finite inputs.

The result is that, with this patch, all math functions now have full
domain error checking (even gamma and lgamma) and code size has decreased
for most ports.  Code size changes in bytes for those with the math module
are:

   unix x64:  -432
unix nanbox:  -792
      stm32:   -88
    esp8266:   +12

Tests are also added to check domain errors are handled correctly.