Fix c_for pretty printer

* calling is_assigned on the loop node always catches the loop index
  assignment...
* reserve was added using the wrong parameter
* c_for_loop was never called and thus completely broken
* reserve implementation was buggy too

outch...
Add missing std::forward
Unrolled, recursive version of array offset computation
Fix bad combiner ordering

In one must first assign a type to the lhs before combining its type
with another, otherwise an incomplete type information is used.
Strict conformance to numpy's complex handling

std::complex and numpy complex behave in slightly different ways...
See pythran/pythonic/patch/README.rst for the motivation and choices.

Thanks to Pierrick for the patch for operator/
Merge pull request #317 from serge-sans-paille/fix-complex-multiply

Strict conformance to numpy's complex handling
Merge pull request #336 from serge-sans-paille/fix-ndarray-combiner

Fix ndarray combiner
Enable pep8 check with travis
Merge pull request #333 from pbrunet/pep8check

Enable pep8 check with travis
Fix complex division

Thanks to pbrunet!
Fix various issues with complex numbers

* complex number and numpy_binary_op did not play well together
* conj and conjugate where not available as methods
* more validation
* move conjugate to __dispatch__
Relax constraints on methods unicity

They are not viable in case of explicit method calls.
As a side effect, test all dispatched method calls both as explicit call
or method calls.
Suppress __classname__ horror

Classes are now proper and regular members of their parent module, no
need for the __classname__ trick horror.

Many ugly hooks are suppressed here and there thanks to this cleanup.

Huge thanks to Pierrick for his preparatory work!