Add xhr prop

[ilyasakin]

I have added xhr prop which you use when you need to stream like JWT protected content. https://github.com/goldfire/howler.js#xhr-object-null

[Stenerson]

Thanks @iakindev! Ahh it looks like I merged the xhrWithCredentials PR (#77) right after Howler removed it 🤦

@andfk, not sure if you want to weigh in... 🤷‍♂️

I think I'll plan to merge this now and remove xhrWithCredentials in a future release. I don't love the duplication of withCredentials but it seems that the xhr prop allows more options that will be useful and at this point removing xhrWithCredentials becomes a breaking change (again 🤦)

I'll give it at least a day or so for people to weigh in. 🙏

[andfk]

@Stenerson 100% agree by using the xhr prop instead :)

Many thanks @iakindev

[ilyasakin]

Sounds like everybody is agreed. So I thought I might as well remove xhrWithCredentials myself.
@Stenerson, if you worried about breaking change please feel free to not include latest commit to merge.

Thanks!

[Stenerson]

Thanks @iakindev actually I think this is ok - I'll plan to cut a new major release this weekend that requires >= 2.2.0 (the howler version that changed this functionality) and also incorporates these changes. Thanks both!

Side note: I wish Howler followed semver rather than including a known breaking change in 2.2.0 🤷‍♂️