Set utf-8 encoding for every open call

[berinhard]

Fixes #190

[berinhard]

Hey @imlimws, maybe this PR can fix the issue you've ran. Since I don't know how to change my system's global encoding to use the same as yours (cp949), can you try to use this branch's pyp5js version and not the one from Pypi and check if the fix works? Feel free to add comments with any other eventual encoding problem you face.

To replace your pyp5js installation, please run:

# depending on how you've installed it first, you may need to use sudo to both uninstall and install
$ pip uninstall pyp5js 
$ pip install git+https://github.com/berinhard/pyp5js.git@bugfix/utf-8-encoding

Thanks,