Add `iter` parameter

Train for `iter` epochs
Fix timings
Remove line-ending whitespace
Relax test requirements

Travis CI previously failed (only for Python 3.4)
Revert "Relax test requirements"

This reverts commit 7fb86513547bec5d120a310aab24e8c7ce3272de.
Use corpus repetition instead

Added a new class in utils to repeat a `corpus` n times.

We could use `RepeatCorpus`, but we would need to compute the number of
sentences beforehand.
No need for self.iter
Correct total_words
Reduce memory requirements
Corpora slicing

- Corpora now implement slicing syntax. For example, corpus[::2] gives
  you even documents
- Re-serialize corpora to generate matching .index files
- Make IndexedCorpus return a SlicedCorpus (generator)
Merge pull request #246 from piskvorky/corpora_slicing

Corpora slicing
Parameterize the downweighting aka Tau_0 in LDA's rho
Change wording for Tau_0 to offset. Update LdaMulticore
Distributed LDA/LSI Python3 compatibility

Fixed import of the queue/Queue module to be compatible with
both Python2 and Python3
Merge pull request #249 from bonzanini/distributed-py3

Distributed LDA/LSI Python3 compatibility
update version of dependencies
Merge branch 'develop' of github.com:piskvorky/gensim into develop
Attempt to fix ImportError: No module named numpy on package installation
Merge pull request #251 from avanov/develop

Fix ImportError: No module named numpy on package installation
Merge pull request #243 from sebastien-j/iter

Add `iter` parameter