Re-enable testsuite for numpy

* relative path for test cases that opened file where wrong
* every numpy test cases raised an exception and were not run
* some runas entries had syntax errors

The reason behind this was that exception raised during testing were a
bit too eagerly trapped and not raised...
Fix extended slice with implicit dimension
Fix dangling ref in ndarray implementations

For performance reason, it is important to take a ref of the array when
creating a view. However this can end up with dangling references, so
use reference qualifier to distinguish between the two.
Fix result type extraction

One has to remove the const qualifier of the return type to match the
specialization of ``pythran_to_python``
Fix bad implementation of str.strip

Empty string was badly handled
Fix rangeextract test case

There is no pythran converter for generators, so expand the generator to
return a list instead.
Fix bad operator-- for nditerator

What a shame...
Update range tests cases parameters

Testing random routines is always painful :-/
Pythran 0.5 "PyData"
Readd support for bench with correct value
Merge pull request #248 from pbrunet/codespeed

Re-add support for bench with correct value
Avoid memory leak at python<->pythran transfer
Merge pull request #243 from pbrunet/leak

Avoid memory leak at python<->pythran transfer
loop unrolling of one of the core numpy_iexpr loop

One of the critical loop of numpy_iexpr was not unrolled by GCC. In the
new (templated) form, it does, which leads to some performance
improvements.

On the numpy-benchmarks test suite, we never get a slowdown and sometime
get a 10% speedup compared to master.
Allow tuple-subscript for numpy_iexpr
Merge pull request #264 from serge-sans-paille/faster-numpy-iexpr

Force loop unrolling of one of the core numpy_iexpr loop
Remove rosetta random test
Remove empty If statement
Handle omp pragma when useless statement are removed
Fix constant folding

* Do not hide issue catching all exceptions
* Enable constant folding for numpy expressions
* Fix reshape signature
* Fix "make upper" attributs name
* restrict constant expression to really constant cases