Implement ParleyNetwork library with ParleyNetworkSession so you can replace Alamofire with your own network stack

[mat1th]

Implemented in this pr:

• Split up Parley package to Parley and ParleyNetwork. You can now use Parley with your own http network layer. To do so you can implement ParleyNetworkSession.
• Move configuring network settings to the Parley.configure function to make the setup order more clear.
• Rename ParleyNetwork to ParleyNetworkConfig to better represent the what the struct does.
• Make code more strict by using let instead of var.

Open tasks:

• [x] I can not fully test if I did not introduce any memory leaks because of open issue #57
• [x] Can not upload bigger images see #56

[mat1th]

Thanks for this PR @mat1th ! We'll need to review this though, bigger change overall. With a quick look this looks like a separtion we wanna go on with. I've added a few comments while quickly looking at it.

We will respond in more detail when we also looked into it 👍

Thank you, I've resolved or replayed your comments.

[mat1th]

Looks good! We'll test some more though.

Few more comments during the review; also: Seems like we don't need fileprivate inside the Parley class. private should work fine since the extension is in the same file, right?

Meaning that:

* secret

* pushToken

* pushType

* pushEnabled

* referrer

* userAuthorization

* userAdditionalInformation

* configure (the one outside the extension)

* reconfigure

* clearChat

* registerDevice

* handleMessage

* handleEvent

Can remain private instead of fileprivate, correct?

(note that some of these weren't due to your changes, they werent private in the previous version either we see)

I've marked them as private now. Could you recheck because I've also re-based the branch with develop.

[mat1th]

Hi @alexkok what is the status on this pr? Are there things that needs to be done on my side?

[alexkok]

Hi @mat1th , thanks! Your PR looks good, we also tested it, no changes needed from your side currently.

FYI: we'll additionally do some more changes for the 4.0.0 release, since it's a major one. Concerning the network separation (this PR), we don't expect changes on the calling side of Parley. Might there be any, they won't be big.

We're on it, and will merge this PR soon to the update/4.0.0 branch, which will be receiving some more changes for the 4.0.0 release.

[mat1th]

Thanks for the update. Great that you are working on more improvements for the 4.0 release.

[alexkok]

This one has now been merged to the update/4.0.0 branch 🚀

4.0.0 will get some changes though

[alexkok]

@mat1th coming back to this one, with 4.0.0 we actually did a few adjustments to the calling side of this.

Not sure if you've seen them already. They are not big, but wanted to let you know in advance before we release 4.0.0:

• The ParleyNetworkSession callback to retrieve an UIImage has been removed, we handle it with the callback now that returns data (Parley will handle the conversion to UIImage etc.)
• The ParleyNetworkSession callback won't have an Error as error completion, but a HTTPErrorResponse instead which contains the error. Since we also need the other data in some cases.
• We'll prefix HTTPRequestMethod HTTPDataResponse HTTPErrorResponse RequestCancelable with Parley due to the possibility of name clashing in Swift.

You can check with the current update/4.0.0 branch, only the latter change (the Parley prefix) is not in there yet. That will be tomorrow.