Remove support for ModHashes and cookie auth

[CrustyJew]

Unless someone can give some compelling reasons to keep the legacy stuff in, I'm starting to remove support for relying on ModHashes as it will help clean up some code and they aren't necessary with OAuth.

One of the main complaints about OAuth was that it was harder to use with bots, now that there is an implementation BotWebAgent which handles token expiration for you, I don't think this should be a major issue any more.

[pimanac]

Kill it with fire.

[james7132]

If done, it would probably be best to provide links to or provide proper documentation for the proper usage in the README.

[chuggafan]

Well, the legacy stuff still works until reddit decides to retire it, so why remove perfectly valid functionality?

[CrustyJew]

The issue is mostly support and having to maintain both versions. It's not really worth it to try and bend code to work with a past implementation that has been deprecated forever and who knows when it will finally be removed. The replacement has been simplified enough that there isn't any good reason that I can see to still use the old methods.

[CrustyJew]

#85 related merge