ENH User model (#1525)

* Started to write Base class for pymc3.models

* mode `add_var` to public api

* Added some docstrings

* Added some docstrings

* added getitem and fixed a typo

* added assertion check

* added resolve var method

* decided not to add resolve method

* Added linear component

* Docs fix

* patsy's intercept is inited properly now

* refactored code

* updated docs

* added possibility to init coefficients with random variables

* added glm

* refactored api, fixed formula init

* refactored linear model, extended acceptable types

* moved useful matrix and labels creation to utils file

* code style

* removed redundant evaluation of shape

* refactored resolver for constructing matrix and labels

* changed error message

* changed signature of init

* simplified utils any_to_tensor_and_labels code

* tests for `any_to_tensor_and_labels`

* added docstring for `any_to_tensor_and_labels` util

* forgot to document return type in `any_to_tensor_and_labels`

* refactored code for dict

* dict tests fix(do not check labels there)

* added access to random vars of model

* added a shortcut for all variables so there is a unified way to get them

* added default priors for linear model

* update docs for linear

* refactored UserModel api, made it more similar to pm.Model class

* Lots of refactoring, tests for base class, more plain api design

* deleted unused module variable

* fixed some typos in docstring

* Refactored pm.Model class, now it is ready for inheritance

* Added documentation for Model class

* Small typo in docstring

* nested contains for treedict (needed for add_random_variable)

* More accurate duplicate implementation of treedict/treelist

* refactored treedict/treelist

* changed `__imul__` of treelist

* added `root` property and `isroot` indicator for base model

* protect `parent` and `model` attributes from violation

* travis' python2 did not fail on bad syntax(maybe it's too new), fixed

* decided not to use functools wrapper

 Unfortunately functools wrapper fails
 when decorating built-in methods so I
 need to fix that improper behaviour.
 Some bad but needed tricks were implemented

* Added models package to setup script

* Refactor utils

* Fix some typos in pm.model

Author: ferrine

pymc3/model.py

@@ -1,5 +1,6 @@
 import threading
 import six
+
 import numpy as np
 import theano
 import theano.tensor as tt