Since selecting the class obeys a static “namespace-id → class” mapping,
I select the class to be instantiated with a dict.

Refs #127

In this case, we can just use the bound method `self.__next__` instead
of calling the unbound method of `type(self)` and giving `self` as the
first parameter.

Fix #127

Refs #47

These have been done automatically by my editor (in the form of a post
save hook).

Remove python2.6 from
- Travis
- Tox
- PyPi tags
- documentation and readme

Also, Simplify an import clause.

This fixes #133

Looks like a buggy pip version could be the root cause, but
nevertheless, we shouldn't need to specify that we're depending on
requests explicitly when requests_oauthlib depends on it.

(https://stackoverflow.com/questions/27497470/setuptools-finds-wrong-package-during-install)

- Adds link to the user guide from readme
- Adds a new page to the user guide on "working with files"

Add OAuth and update docs

This follows on from #114 and addresses #87, providing an `end`
arg for all these generators, letting you get 'all pages between
Bar and Foo' or whatever it is you may need.

`redefined-builtin` and `too-many-arguments` are small smells,
and fixing them would break backward compat.

Also letting pylint know that we need the imports in __init__.py

* make basic_edit.py and upload.py python-3 compatible

Beaware argument requests from the constructor has been rename reqs

Add 'end' argument to PageList

this is sometimes useful; for instance I have a use case for
getting all pages in a given namespace that are alphabetically
between two specific points (because their names are in a
predictable format that involves alphabetically-sorted dates).
'end' is added as the last kwarg to avoid breaking any current
uses that rely on the kwarg ordering (thanks dan for pointing
that out).

I'll create a CREDITS.md file containing the info removed on this commit and more, so we have a comprehensive history document.

Use 'exec' in py3-compatible manner

[#106] fix GeneratorList with Python 3 (add __next__)

Credit for this fix goes to @tosher:
https://github.com/mwclient/mwclient/issues#issuecomment-154751657
I just figured out exactly what changes his comment suggested,
and poked around a bit to figure out what was going on and why
they're needed.

`GeneratorList` (and things deriving from it, e.g. `Category`)
was broken for iteration purposes in Python 3. In Python 3
the iterator protocol requires a `__next__` method, not a `next`
method as in Python 2. 8d0650cd renamed `List`'s `next` method
to `__next__` and added a small wrapper `next` method to account
for this, but did not make the same change for `GeneratorList`.
So when you iterate over a `GeneratorList` with Python 3, it
winds up calling `List.__next__` (since `GeneratorList` inherits
from `List`), not `GeneratorList.next`. So we don't hit the bit
that turns the results into mwclient page objects, and just get
the raw dicts from the `List` method.

We also have to change a couple of direct calls to `List.next`
to call `List.__next__` instead. If we don't do this, then when
the call originates from a child class, things get messed up,
because `List.next` calls `self.__next__` - and that will wind
up calling the child class' `__next__`, not `List`'s `__next__`.

Confused yet? :)