Merge pull request #44 from Nagadum/genex_transform

Genex transform
Store ideas for new pythraners in a TODO list.

And automagically put it on the web, of course.
Fix bug in GenExpToImap ordering

It is invalid to call this pass before all tuple unpacking have been
done.
Alpha support for the bisect module.

Just enough to pass a new test case.
Rework latest Nagadum commit.

Make sure everything is pep8 compliant, event if it leads to a less
interesting docstring.
Support tuple -> list conversion

Useful whenever tuples are not supported by pythran: just convert them
to a list (if it is meaningful). For instance to iterate over a tuple...
Huge rework of itertools

* indent everything properly
* use std::forward to avoid unnecessary copies
* do not store the value computed by the operator*

As a result, izip and imap are really faster (x2 on a bench here), I did
not implement the same optimizations for ifilter and generate. Yet.
Fix ExpandImport ordering

It should be called sooner, otherwise some analysis choke on an unknown
identifiers which turns out to be a name imported from a module.
Rework generator representation

Still not perfect, but at least does not lead to bugs in the validation.
Itertools corrections and optimizations.

* ifilter and product optimization (no more useless copy)
* using random_access iterators when possible, foarward iterators otherwise
* itertools tests now use complex generator expressions