Fix string representation of complex numbers with negative zeroes.
Fix string representation of complex numbers with negative zeroes.

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