Fix several bugs in sliced_ndarray implementation

Fix several bugs when slicing a sliced_ndarray.
Thanks to the great recursive fft example from Adrien merlini.
Add import * expansion

Replace import * by using module defined in tables.py
Fix bad module naming when using custom output, again

This mostly reverts commit d0f4149c2a426ad136bab6559bc2dd1c712492b4
and fixes the issue described.
Fix OMP detection to look into LD_LIBRARY_PATH env variable
Merge pull request #120 from ogrisel/omp-detection-fix

Fix OMP detection to look into LD_LIBRARY_PATH env variable
Merge pull request #118 from joker-eph/toolchain

Fix bad module naming when using custom output, again …
Clean code for omp class
Merge pull request #121 from joker-eph/toolchain

Clean code for omp class
Fix implementation of core::array

Previous implementation was using list initialization which implied an
extra copy. This was problematic as core::array is used for ndarray
indexing. Using the aggregate constructor prevents the issue, but it is
incompatible with inheritance (has confirmed by @jfalcou).

Has the implementation of std::array is straight forward, I duplicated it
in our code and extended it. Note that this is motivated by a huge
performance gain (+30% speedup on some benchmarks).
Merge pull request #124 from serge-sans-paille/rework-core-array

Fix implementation of core::array
Remove debug trace in the brownian test case

Better be silent not to pollute stdout with irrelevant info.
Add test case from Issue #122

Marked as skipped as there is no simple way for Pythran to support this.
Add diffusion as test case

* Pythran performs well on the pure python code but not on the numpy version.
Merge branch 'yuancheng-yuanchengBranch'
Fix value_type for numpy_expr

* value_type of : empty_like(ndarray<long, 2>) should be ndarray<long,1> instead of long
Add dtype and T attributes to numpy array
Fix shape for gslice

* case of gslice without all its dimension named in the slice
* ex: a.shape = (2,3,4)
    b = a[:,1]
    print b.shape
gslice are built from const array
Rework None implementation

Previous implementation had typing information spread over several files
(bad locality) and did not handle using member function on the none
type.
Add missing const qualifier for string::operator==