Finish porting the cmath module from C to Python.
Finish porting the cmath module from C to Python.

brython-dev/brython,kikocorreoso/brython,Hasimir/brython,brython-dev/brython,jonathanverner/brython,jonathanverner/brython,brython-dev/brython,jonathanverner/brython,kikocorreoso/brython,Hasimir/brython,jonathanverner/brython,Hasimir/brython,kikocorreoso/brython,Hasimir/brython