Added optional encoding to dump and load functions

[Backist]

No description provided.

[Backist]

As i said in the issue, it is a minimal change but I think it is useful especially when you need to use a different encoding than the one your system uses, for example utf-8 instead of cp1292 which is used when the encoding parameter is not specified in open().

[bobfang1992]

Thanks, merged.

[bobfang1992]

@Backist it seems the ut are faling after I merge this, I can take a look at this later but if you have time please do not hesitate to have a look as well. Thanks!

[Backist]

The wheel error is essentially fixed, I just made a syntax error. I checked with the tests that the binary modes did not take the enconding argument as None, since the binary opening mode does not take an enconding.
I will make a new pull request with the hotfix.
Ignore that revert commit, I just created it by mistake

[Backist]

I'm a bit busy at the moment, let me have a look at it in depth as soon as I can verify with the tests before I do the final PR.

[bobfang1992]

@Backist sure thanks!