Add smart information retrieval system for TfidfModel. Fix #1785 (#…

…1791)

* fixing appveyor

* verify weights

* verify weights

* smartirs ready

* change old tests

* remove lambdas

* address suggestions

* minor fix

* pep8 fix

* fix pickle problem

* flake8 fix

* fix bug in docstring

* added few tests

* fix normalize issue for pickling

* fix normalize issue for pickling

* test without sklearn api

* hanging idents and new tests

* add docstring

* add docstring

* better way cmparing floats

* old way of cmp floats

* doc fix[1]

* doc fix[2]

* fix description TODOs

* fix irksome comparision

docs/src/models/tfidfmodel.rst

@@ -1,9 +1,10 @@
 :mod:`models.tfidfmodel` -- TF-IDF model
-======================================================
+========================================
 
 .. automodule:: gensim.models.tfidfmodel
     :synopsis: TF-IDF model
     :members:
     :inherited-members:
     :undoc-members:
     :show-inheritance:
+    :special-members: __getitem__