Enable users to provide custom implementation for the Dialog.

[fineswap]

This is a preliminary work to provide a Factory-based class which abstracts much of under-the-hood implementation in the library. A first implementation deals with Dialogs.

[fineswap]

@vineetmobile

This is a first pull for, hopefully, more to come. The idea is to abstract most of the internal parts so that users could be able to customize the look-and-feel of pages, dialogs and other views in the library.

I tried my best not to change the API as it stands now, and I added @deprecated notices where appropriate.

[vineetmobile]

Hi,

Thanks for pull request. We are currently looking to change architecture. So rejecting pull request. Once done, we will welcome pull request

[fineswap]

@vineetmobile
Thanks for the heads up. Let's hope it will take a short time.