Better error message.
Don't reorder dimensions for elemwise when there is 0 or 1 dimensions.

this add extra useless code.
Add ScalarOp.c_code_contiguous interface and use it with exp.

Do this for amdlibm.

There is code for sigmoid, but it is disabled as it is slower.
Add contig version of pow, cos, sin, log, log2, log10
add amdlibm code for powx (pow(tensor, scalar))
fix test crash in debugmode.

it was triing the Image2Neibs.perform method for GpuImage2Neibs.
Fix Elemwise and CAReduce version when the scalar_op don't have a version.

We were not returning () when the scalar op don't have a version.
Merge pull request #1389 from nouiz/sigmoid

Sigmoid
Collections.Counter added for python < 2.7
better comment.
remove import not used.
Allow other file to reuse tensor/tests/test_basic.py:MakeTester
Add ultra_fast_sigmoid.
Merge pull request #1390 from memimo/counter

Collections.Counter added for python < 2.7
Add SigmoidTester and SoftplusTester
Allow to pass rtol and atol to TensorType.values_eq_approx
Added doc about ultra_fast_sigmoid.
Merge pull request #1391 from nouiz/sigmoid

Add ultra_fast_sigmoid
Add, document and test hard_sigmoid.
Fix doc indentation. They are part of their section, not at the global scope.